diff --git a/applications/test/HashTable1/Test-HashTable1.C b/applications/test/HashTable1/Test-HashTable1.C
index 6f92ffcd8f..75e4eeda2d 100644
--- a/applications/test/HashTable1/Test-HashTable1.C
+++ b/applications/test/HashTable1/Test-HashTable1.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2017-2021 OpenCFD Ltd.
+    Copyright (C) 2017-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -33,7 +33,7 @@ License
 #include "IOstreams.H"
 #include "StringStream.H"
 #include "ListOps.H"
-#include "StringListOps.H"
+#include "stringListOps.H"
 
 using namespace Foam;
 
@@ -71,9 +71,18 @@ int main()
         << "table1 [" << table1.size() << "] " << endl;
     forAllConstIters(table1, iter)
     {
-        Info<< iter.key() << " => " << iter() << nl;
+        Info<< iter.key() << " => " << iter.val() << nl;
     }
 
+
+    Info<< "\ntable1 sorted() :" << endl;
+    for (const auto& iter : table1.sorted())
+    {
+        Info<< "    " << iter.key() << " => " << iter.val() << nl;
+    }
+    Info<< endl;
+
+
     table1.set("acr", 108);
     table1.set("adx", 109);
     table1.set("aec", 100);
@@ -82,6 +91,22 @@ int main()
 
     Info<< "\noverwrote some values table1: " << table1 << endl;
 
+
+    // Test writable sorted access
+    for (auto& iter : table1.sorted())
+    {
+        // Should not compile:  iter.key() = "illegal";
+        iter.val() *= 2;
+    }
+
+    Info<< "\nInplace modified - via sorted() access :" << endl;
+    for (const auto& iter : table1.sorted())
+    {
+        Info<< "    " << iter.key() << " => " << iter.val() << nl;
+    }
+    Info<< endl;
+
+
     Info<< "\ntest find:" << endl;
     Info<< table1.find("aaa")() << nl
         << table1.find("aba")() << nl
diff --git a/applications/test/IOField/Test-IOField.C b/applications/test/IOField/Test-IOField.C
index 97a4774b61..729a7c85e5 100644
--- a/applications/test/IOField/Test-IOField.C
+++ b/applications/test/IOField/Test-IOField.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2017 OpenFOAM Foundation
-    Copyright (C) 2019-2021 OpenCFD Ltd.
+    Copyright (C) 2019-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -34,6 +34,7 @@ Description
 
 #include "argList.H"
 #include "IOField.H"
+#include "IOList.H"
 #include "primitiveFields.H"
 #include "polyMesh.H"
 #include "Time.H"
@@ -181,6 +182,7 @@ int main(int argc, char *argv[])
     argList::addBoolOption("bool", "Use bool for tests");
     argList::addBoolOption("scalar", "Use scalar for tests");
     argList::addBoolOption("label", "Use label for tests (default)");
+    argList::addBoolOption("ref", "Test writing by ref");
 
     #include "addTimeOptions.H"
 
@@ -232,6 +234,36 @@ int main(int argc, char *argv[])
         doTests<label>(io, sz);
     }
 
+    if (args.found("ref"))
+    {
+        Info<< nl << "Testing writing referenced external data" << nl << endl;
+
+        IOobject ioOutput
+        (
+            args.executable(),
+            "constant",
+            runTime,
+            IOobject::NO_READ,
+            IOobject::NO_WRITE,
+            false
+        );
+
+        labelList ints(identity(200));
+
+        ioOutput.rename(args.executable() + "-labels");
+        Info<< "write " << ioOutput.objectRelPath() << endl;
+        {
+            IOListRef<label>(ioOutput, ints).write();
+        }
+
+        ioOutput.rename(args.executable() + "-points");
+        Info<< "write " << ioOutput.objectRelPath() << endl;
+        {
+            IOFieldRef<vector>(ioOutput, mesh.points()).write();
+        }
+
+    }
+
 
     Pout<< "\nEnd\n" << endl;
 
diff --git a/applications/test/ITstream/Test-ITstream.C b/applications/test/ITstream/Test-ITstream.C
index 1503a43977..30d74df2ab 100644
--- a/applications/test/ITstream/Test-ITstream.C
+++ b/applications/test/ITstream/Test-ITstream.C
@@ -34,7 +34,7 @@ Description
 #include "argList.H"
 #include "ITstream.H"
 #include "ListOps.H"
-#include "StringListOps.H"
+#include "stringListOps.H"
 
 using namespace Foam;
 
diff --git a/applications/test/ListOps/Test-ListOps.C b/applications/test/ListOps/Test-ListOps.C
index ea034e57b5..e3db28c7ff 100644
--- a/applications/test/ListOps/Test-ListOps.C
+++ b/applications/test/ListOps/Test-ListOps.C
@@ -151,6 +151,10 @@ int main(int argc, char *argv[])
         << subsetList(test6, evenNonZero) << nl
         << endl;
 
+    Info<< "Subset of non-zero, even values: "
+        << IndirectList<label>::subset_if(test6, evenNonZero) << nl
+        << endl;
+
     test6.append(identity(13, 12));
 
     Info<< "Randomized: " << flatOutput(test6) << endl;
diff --git a/applications/test/PtrList/Test-PtrList.C b/applications/test/PtrList/Test-PtrList.C
index 488618e0b3..a8cf8686af 100644
--- a/applications/test/PtrList/Test-PtrList.C
+++ b/applications/test/PtrList/Test-PtrList.C
@@ -59,7 +59,7 @@ public:
 
     ~Scalar()
     {
-        Info<<"delete Scalar: " << data_ << endl;
+        Info<< "delete Scalar: " << data_ << endl;
     }
 
     const scalar& value() const
@@ -324,7 +324,7 @@ int main(int argc, char *argv[])
         list1.set(i, new Scalar(1.3*i));
     }
 
-    Info<<"Emplace set " << list2.size() << " values" << nl;
+    Info<< "Emplace set " << list2.size() << " values" << nl;
     forAll(list2, i)
     {
         list2.emplace(i, (10 + 1.3*i));
@@ -338,9 +338,9 @@ int main(int argc, char *argv[])
 
 
     Info<< nl
-        <<"list1: " << list1 << nl
-        <<"list2: " << list2 << nl
-        <<"list-appended: " << listApp << endl;
+        << "list1: " << list1 << nl
+        << "list2: " << list2 << nl
+        << "list-appended: " << listApp << endl;
 
 
     // Release values
@@ -357,27 +357,27 @@ int main(int argc, char *argv[])
             }
         }
 
-        Info<<"Released pointers from";
+        Info<< "Released pointers from";
         print(Info, listApp) << nl;
 
-        Info<<"Into plain list of pointers";
+        Info<< "Into plain list of pointers";
         print(Info, ptrs) << nl;
 
         PtrDynList<Scalar> newlist1(ptrs);
 
-        Info<<"Constructed from plain list of pointers";
+        Info<< "Constructed from plain list of pointers";
         print(Info, ptrs) << nl;
         print(Info, newlist1) << nl;
     }
 
 
-    Info<<"indirectly delete some items via set(.., nullptr) :" << endl;
+    Info<< "indirectly delete some items via set(.., nullptr) :" << endl;
     for (label i = 2; i < 5; i++)
     {
         list1.set(i, nullptr);
     }
 
-    Info<<"release some items:" << endl;
+    Info<< "release some items:" << endl;
 
     for (label i = -2; i < 5; i++)
     {
@@ -389,31 +389,31 @@ int main(int argc, char *argv[])
         }
     }
 
-    Info<<"list1: ";
+    Info<< "list1: ";
     print(Info, list1) << nl;
 
     list1.resize(list1.squeezeNull());
-    Info<<"squeezed null: ";
+    Info<< "squeezed null: ";
     print(Info, list1) << nl;
 
-    Info<<"transfer list2 -> list1:" << endl;
+    Info<< "transfer list2 -> list1:" << endl;
     list1.transfer(list2);
 
-    Info<<"list1: " << list1 << nl
-        <<"list2: " << list2 << endl;
+    Info<< "list1: " << list1 << nl
+        << "list2: " << list2 << endl;
 
-    Info<<"indirectly delete some items via setSize :" << endl;
+    Info<< "indirectly delete some items via setSize :" << endl;
     list1.setSize(4);
 
-    Info<<"list1: " << list1 << endl;
+    Info<< "list1: " << list1 << endl;
 
     {
         PtrList<Scalar> list1a(list1, false);
 
-        Info<<"Clone constructed" << endl;
-        Info<<"in:  " << list1 << nl
-            <<"out: " << list1a << nl
-            <<"addresses:" << nl;
+        Info<< "Clone constructed" << endl;
+        Info<< "in:  " << list1 << nl
+            << "out: " << list1a << nl
+            << "addresses:" << nl;
         printAddr(Info, list1);
         printAddr(Info, list1a);
         Info<<"values:" << nl;
@@ -423,112 +423,112 @@ int main(int argc, char *argv[])
         {
             auto* ptr = &(list1a.first());
             list1a.set(0, ptr);
-            Info<<"values:" << nl;
+            Info<< "values:" << nl;
             print(Info, list1a);
         }
 
 
         PtrList<Scalar> list1b(list1a, true);
 
-        Info<<"Reuse constructed" << endl;
-        Info<<"in:  " << list1a << nl
-            <<"out: " << list1b << nl
-            <<"addresses:" << nl;
+        Info<< "Reuse constructed" << endl;
+        Info<< "in:  " << list1a << nl
+            << "out: " << list1b << nl
+            << "addresses:" << nl;
         printAddr(Info, list1a);
         printAddr(Info, list1b);
 
 
         PtrList<Scalar> list1c(list1b.clone());
 
-        Info<<"Explicit clone()" << endl;
-        Info<<"in:  " << list1b << nl
-            <<"out: " << list1c << nl
-            <<"addresses:" << nl;
+        Info<< "Explicit clone()" << endl;
+        Info<< "in:  " << list1b << nl
+            << "out: " << list1c << nl
+            << "addresses:" << nl;
         printAddr(Info, list1b);
         printAddr(Info, list1c);
     }
 
     PtrList<Scalar> list3(std::move(list1));
-    Info<<"Move constructed" << endl;
+    Info<< "Move constructed" << endl;
 
-    Info<<"list1: " << list1 << nl
-        <<"list2: " << list2 << nl
-        <<"list3: " << list3 << endl;
+    Info<< "list1: " << list1 << nl
+        << "list2: " << list2 << nl
+        << "list3: " << list3 << endl;
 
 
-    Info<<"Move construct:" << endl;
+    Info<< "Move construct:" << endl;
 
     PtrList<Scalar> list4(std::move(list3));
 
-    Info<<"list3: " << list3 << nl
-        <<"list4: " << list4 << endl;
+    Info<< "list3: " << list3 << nl
+        << "list4: " << list4 << endl;
 
-    Info<<"Move assign:" << endl;
+    Info<< "Move assign:" << endl;
     list3 = std::move(list4);
 
-    Info<<"list3: " << list3 << nl
-        <<"list4: " << list4 << endl;
+    Info<< "list3: " << list3 << nl
+        << "list4: " << list4 << endl;
 
 
-    Info<<"UPtrList from PtrList" << nl;
+    Info<< "UPtrList from PtrList" << nl;
 
     UPtrList<Scalar> ulist1(list3);
 
-    Info<<"ulist1: " << ulist1 << nl;
-    Info<<"PtrList addresses:";
+    Info<< "ulist1: " << ulist1 << nl;
+    Info<< "PtrList addresses:";
     printAddr(Info, list3);
-    Info<<"UPtrList addresses:";
+    Info<< "UPtrList addresses:";
     printAddr(Info, ulist1);
     Info<< nl;
 
     {
-        Info<<"UPtrList(const UPtrList&)" << nl;
+        Info<< "UPtrList(const UPtrList&)" << nl;
 
         const UPtrList<Scalar>& cref = ulist1;
 
         UPtrList<Scalar> ulist1cp(cref);
 
-        Info<<"src addresses:";
+        Info<< "src addresses:";
         printAddr(Info, cref);
-        Info<<"dst addresses:";
+        Info<< "dst addresses:";
         printAddr(Info, ulist1cp);
         Info<< nl;
     }
 
 
-    Info<<"Move construct:" << endl;
+    Info<< "Move construct:" << endl;
 
     UPtrList<Scalar> ulist2(std::move(ulist1));
 
-    Info<<"ulist1: " << ulist1 << nl
-        <<"ulist2: " << ulist2 << nl;
+    Info<< "ulist1: " << ulist1 << nl
+        << "ulist2: " << ulist2 << nl;
 
-    Info<<"Copy assign:" << endl;
+    Info<< "Copy assign:" << endl;
     ulist1 = ulist2;
 
-    Info<<"ulist1: " << ulist1 << nl
-        <<"ulist2: " << ulist2 << nl;
+    Info<< "ulist1: " << ulist1 << nl
+        << "ulist2: " << ulist2 << nl;
 
-    Info<<"Move assign:" << endl;
+    Info<< "Move assign:" << endl;
     ulist1 = std::move(ulist2);
 
-    Info<<"ulist1: " << ulist1 << nl
-        <<"ulist2: " << ulist2 << nl;
+    Info<< "ulist1: " << ulist1 << nl
+        << "ulist2: " << ulist2 << nl;
 
     // Test iterator random access
     {
         auto iter1 = ulist1.begin();
         auto iter2 = iter1 + 3;
 
-        Info<<"begin:" << *iter1 << " (+3):" << *iter2 << nl;
+        Info<< "begin:" << *iter1 << " (+3):" << *iter2 << nl;
         Info<< "diff= " << (iter1 - iter2) << nl;
         Info<< "iter[2]=" << iter1[2] << nl;
         Info<< "iter1 < iter2 : " << (iter1 < iter2) << nl;
         Info<< "iter1 >= iter2 : " << (iter1 >= iter2) << nl;
 
-        Info<<"->" << iter1->value() << nl;
-        Info<<"*"  << (*iter1).value() << nl;
-        Info<<"()" << iter1().value() << nl;
+        Info<< "->" << iter1->value() << nl;
+        Info<< "*"  << (*iter1).value() << nl;
+        Info<< "()" << iter1().value() << nl;
     }
 
     PtrList<plane> planes;
@@ -541,7 +541,7 @@ int main(int argc, char *argv[])
         Info<< "    plane " << p << endl;
     }
 
-    Info<<"Testing PtrDynList" << nl;
+    Info<< "Testing PtrDynList" << nl;
 
     PtrDynList<plane> dynPlanes;
 
@@ -566,10 +566,10 @@ int main(int argc, char *argv[])
     report(Info, dynPlanes, true);
 
     dynPlanes.clear();
-    Info<<"clear()" << nl;
+    Info<< "clear()" << nl;
     report(Info, dynPlanes);
 
-    Info<<"now append again" << endl;
+    Info<< "now append again" << endl;
     {
         dynPlanes.append(new plane(vector::one, vector::one));
         dynPlanes.append(new plane(vector(1,2,3), vector::one));
@@ -597,13 +597,13 @@ int main(int argc, char *argv[])
 
         stdPlanes.resize(stdPlanes.squeezeNull());
 
-        Info<<"After pruning nullptr entries" << endl;
+        Info<< "After pruning nullptr entries" << endl;
         printAddr(Info, stdPlanes);
     }
 
     dynPlanes.resize(dynPlanes.squeezeNull());
 
-    Info<<"After pruning nullptr entries" << endl;
+    Info<< "After pruning nullptr entries" << endl;
     report(Info, dynPlanes, true);
 
 
@@ -621,25 +621,48 @@ int main(int argc, char *argv[])
         sortedOrder(dynPlanes2, order);
         Info<< "sorted order: " << flatOutput(order) << nl;
 
-        sortedOrder(dynPlanes2, order, PtrListOps::greater<plane>(dynPlanes2));
+        sortedOrder(dynPlanes2, order, UPtrList<plane>::greater(dynPlanes2));
         Info<< "sorted order: " << flatOutput(order) << nl;
 
+        // Shuffle
+        shuffle(dynPlanes2);
+        Info<< "Shuffled" << endl;
+        report(Info, dynPlanes2, false);
+
+        // Reverse sort
+        sort
+        (
+            dynPlanes2,
+            [](const plane& a, const plane& b) { return (b < a); }
+        );
+        Info<< "Reverse sorted" << endl;
+        report(Info, dynPlanes2, false);
+
+        // Forward sort
         sort(dynPlanes2);
+        Info<< "Sorted" << endl;
+        report(Info, dynPlanes2, false);
+
+        // Reverse pointer list - not yet available or needed!
+        /// reverse(dynPlanes2);
+        /// Info<< "Reversed" << endl;
+        /// report(Info, dynPlanes2, false);
+
         // dynPlanes2.squeezeNull();
 
-        Info<<"Append" << endl;
+        Info<< "Append" << endl;
         report(Info, dynPlanes2, false);
 
         dynPlanes.append(std::move(dynPlanes2));
 
-        Info<<"Result" << endl;
+        Info<< "Result" << endl;
         report(Info, dynPlanes, false);
 
-        Info<<"From" << endl;
+        Info<< "From" << endl;
         report(Info, dynPlanes2, false);
     }
 
-    Info<<"free()" << endl;
+    Info<< "free()" << endl;
 
     dynPlanes.free();
     report(Info, dynPlanes, true);
diff --git a/applications/test/UIndirectList/Test-UIndirectList.C b/applications/test/UIndirectList/Test-UIndirectList.C
index a9d9cabd76..7d6714591a 100644
--- a/applications/test/UIndirectList/Test-UIndirectList.C
+++ b/applications/test/UIndirectList/Test-UIndirectList.C
@@ -27,7 +27,7 @@ Description
 
 \*---------------------------------------------------------------------------*/
 
-#include "UIndirectList.H"
+#include "IndirectList.H"
 #include "DynamicList.H"
 #include "IOstreams.H"
 #include "ListOps.H"
diff --git a/applications/test/bitSet2/Test-bitSet2.C b/applications/test/bitSet2/Test-bitSet2.C
index df04f3ce0f..f53f3e831f 100644
--- a/applications/test/bitSet2/Test-bitSet2.C
+++ b/applications/test/bitSet2/Test-bitSet2.C
@@ -344,12 +344,35 @@ int main(int argc, char *argv[])
 
     Info<< "\noperator|=\n";
     {
+        bitSet a; a.set(labelRange(15, 8));
+        bitSet b; b.set(labelRange(30, 8));
+
+        report(a, false);
+        report(b, false);
+        report((a |= b), true);
+    }
+    {
+        Info<< " other test\n";
+
         bitSet list3 = list1;
         report((list3 |= list2), true);
     }
 
     Info<< "\noperator&=\n";
     {
+        bitSet a; a.set(labelRange(30, 8));
+        bitSet b; b.set(labelRange(0, 8));
+
+        report(a, false);
+        report(b, false);
+        Info<< "  (a & b)\n";
+        report((a & b), true);
+        Info<< "  (b & a)\n";
+        report((b & a), true);
+    }
+    {
+        Info<< " other test\n";
+
         bitSet list3 = list1;
         report((list3 &= list2), true);
     }
diff --git a/applications/test/boolList/Test-boolList.C b/applications/test/boolList/Test-boolList.C
index dd4f79a38f..f3eac1bd62 100644
--- a/applications/test/boolList/Test-boolList.C
+++ b/applications/test/boolList/Test-boolList.C
@@ -157,18 +157,34 @@ int main(int argc, char *argv[])
     {
         boolList list2(5, true);
         list2.unset(2);
+        list2.unset(3);
 
         Info<< "Test wrapper idea" << nl;
 
         bitSetOrBoolList wrapper(list2);
 
-        if (wrapper.test(1))
+        // Use predicate, or test() method
+
+        if (list2(1))
         {
-            Info<< "1 is on" << nl;
+            Info<< "1 is on (original)" << nl;
         }
-        if (!wrapper.test(2))
+        if (!list2(2))
         {
-            Info<< "2 is off" << nl;
+            Info<< "2 is off (original)" << nl;
+        }
+        if (!list2(100))
+        {
+            Info<< "100 is off (original)" << nl;
+        }
+
+        if (wrapper(1))
+        {
+            Info<< "1 is on (wrapped)" << nl;
+        }
+        if (!wrapper(2))
+        {
+            Info<< "2 is off (wrapped)" << nl;
         }
     }
 
diff --git a/applications/test/boolList/bitSetOrBoolList.H b/applications/test/boolList/bitSetOrBoolList.H
index 56e3b9d1f5..98ee9fbac3 100644
--- a/applications/test/boolList/bitSetOrBoolList.H
+++ b/applications/test/boolList/bitSetOrBoolList.H
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2020 OpenCFD Ltd.
+    Copyright (C) 2020-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -32,8 +32,8 @@ Description
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef bitSetOrBoolList_H
-#define bitSetOrBoolList_H
+#ifndef Foam_bitSetOrBoolList_H
+#define Foam_bitSetOrBoolList_H
 
 #include "bitSet.H"
 #include "boolList.H"
@@ -88,6 +88,13 @@ public:
         {
             return bits_.test(i) || bools_.test(i);
         }
+
+        //- Test predicate
+        bool operator()(const label i) const
+        {
+            // Can also use test(i) etc...
+            return bits_(i) || bools_(i);
+        }
 };
 
 
diff --git a/applications/test/boolList/disabledBoolList.H b/applications/test/boolList/disabledBoolList.H
index 7adc481e35..28b3bd69ac 100644
--- a/applications/test/boolList/disabledBoolList.H
+++ b/applications/test/boolList/disabledBoolList.H
@@ -41,8 +41,8 @@ Description
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef disabledBoolList_H
-#define disabledBoolList_H
+#ifndef Foam_disabledBoolList_H
+#define Foam_disabledBoolList_H
 
 /*---------------------------------------------------------------------------*\
                       Class disabledBoolList Declaration
@@ -60,6 +60,9 @@ struct disabledBoolList
     bool test(int) const { return true; }
 
     void set(bool) {}
+
+    // Perhaps not?
+    /// bool operator()(const label i) const { return true; }
 };
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
diff --git a/applications/test/cplusplus1/Test-cpluplus1.C b/applications/test/cplusplus1/Test-cpluplus1.C
index 37a4853ec0..8b86ee33c8 100644
--- a/applications/test/cplusplus1/Test-cpluplus1.C
+++ b/applications/test/cplusplus1/Test-cpluplus1.C
@@ -31,7 +31,7 @@ Description
 #include "string.H"
 #include "macros.H"
 #include "IOstreams.H"
-#include "UList.H"
+#include "List.H"
 #include "HashSet.H"
 
 #include <typeinfo>
diff --git a/applications/test/minMax1/Test-minMax1.C b/applications/test/minMax1/Test-minMax1.C
index 10f1a9e9e2..664a3a7f22 100644
--- a/applications/test/minMax1/Test-minMax1.C
+++ b/applications/test/minMax1/Test-minMax1.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019 OpenCFD Ltd.
+    Copyright (C) 2019-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -190,6 +190,8 @@ int main(int argc, char *argv[])
             << nl;
 
         Info<< "Subset = " << subsetList(values1, limiter) << nl;
+        Info<< "Subset = "
+            << IndirectList<scalar>::subset_if(values1, limiter) << nl;
 
         Info<< nl << "test clip() with limiter: " << limiter << nl;
         for (const scalar& val : values1)
diff --git a/applications/test/primitivePatch/Test-PrimitivePatch.C b/applications/test/primitivePatch/Test-PrimitivePatch.C
index 86a6b5060c..9a7e577676 100644
--- a/applications/test/primitivePatch/Test-PrimitivePatch.C
+++ b/applications/test/primitivePatch/Test-PrimitivePatch.C
@@ -32,7 +32,6 @@ Description
 #include "argList.H"
 #include "Time.H"
 #include "polyMesh.H"
-#include "primitiveFacePatch.H"
 #include "primitivePatch.H"
 #include "IndirectList.H"
 #include "Fstream.H"
diff --git a/applications/test/processorTopology/Test-processorTopology.C b/applications/test/processorTopology/Test-processorTopology.C
index 1d8d7fab1a..c4e87c8868 100644
--- a/applications/test/processorTopology/Test-processorTopology.C
+++ b/applications/test/processorTopology/Test-processorTopology.C
@@ -44,7 +44,7 @@ int main(int argc, char *argv[])
     argList::noFunctionObjects();
     argList::addNote
     (
-        "Create a metis graph file representation for an OpenFOAM mesh"
+        "Create graph of OpenFOAM mesh connections"
     );
 
     #include "setRootCase.H"
@@ -59,9 +59,9 @@ int main(int argc, char *argv[])
     #include "createTime.H"
     #include "createPolyMesh.H"
 
-    const globalMeshData& globData = mesh.globalData();
-
-    const labelListList& connectivity = globData;
+    // Adjacency table
+    const labelListList& connectivity =
+        mesh.globalData().topology().procNeighbours();
 
     if (Pstream::master())
     {
diff --git a/applications/test/sort/Test-sortList.C b/applications/test/sort/Test-sortList.C
index 5e6f4f3813..04b17185fe 100644
--- a/applications/test/sort/Test-sortList.C
+++ b/applications/test/sort/Test-sortList.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011 OpenFOAM Foundation
-    Copyright (C) 2017-2019 OpenCFD Ltd.
+    Copyright (C) 2017-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -28,7 +28,9 @@ Description
 
 \*---------------------------------------------------------------------------*/
 
+#include "SortList.H"
 #include "SortableList.H"
+#include "IndirectList.H"
 #include "ListOps.H"
 #include "HashSet.H"
 #include "stringOps.H"
@@ -49,6 +51,18 @@ void printInfo(const SortableList<T>& list)
 
 int main(int argc, char *argv[])
 {
+    {
+        const labelList orig({7, 9, 7, 12, 9, 1, 12, 2, 4, 7, 4, 0});
+
+        Info<< "original list: " << flatOutput(orig) << endl;
+
+        auto unique = IndirectList<label>::uniq(orig);
+
+        Info<< "unique  list: " << flatOutput(unique) << endl;
+        Info<< "unique  idx : " << flatOutput(unique.addressing()) << endl;
+    }
+
+
     const labelList orig({7, 9, 1, 2, 4, 7, 4, 0});
 
     labelList order;
diff --git a/applications/utilities/finiteArea/checkFaMesh/checkFaMesh.C b/applications/utilities/finiteArea/checkFaMesh/checkFaMesh.C
index e15b830083..2aaede0be8 100644
--- a/applications/utilities/finiteArea/checkFaMesh/checkFaMesh.C
+++ b/applications/utilities/finiteArea/checkFaMesh/checkFaMesh.C
@@ -45,7 +45,7 @@ Original Authors
 #include "areaFields.H"
 #include "edgeFields.H"
 #include "processorFaPatch.H"
-#include "foamVtkUIndPatchWriter.H"
+#include "foamVtkIndPatchWriter.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
diff --git a/applications/utilities/finiteArea/makeFaMesh/makeFaMesh.C b/applications/utilities/finiteArea/makeFaMesh/makeFaMesh.C
index 82f9c233a3..5470eb5fb2 100644
--- a/applications/utilities/finiteArea/makeFaMesh/makeFaMesh.C
+++ b/applications/utilities/finiteArea/makeFaMesh/makeFaMesh.C
@@ -49,7 +49,7 @@ Original Authors
 #include "faFieldDecomposer.H"
 #include "faMeshReconstructor.H"
 #include "PtrListOps.H"
-#include "foamVtkUIndPatchWriter.H"
+#include "foamVtkIndPatchWriter.H"
 #include "OBJstream.H"
 
 using namespace Foam;
diff --git a/applications/utilities/mesh/generation/extrude/extrudeMesh/extrudeMesh.C b/applications/utilities/mesh/generation/extrude/extrudeMesh/extrudeMesh.C
index 680eb5815e..bc5fba6e60 100644
--- a/applications/utilities/mesh/generation/extrude/extrudeMesh/extrudeMesh.C
+++ b/applications/utilities/mesh/generation/extrude/extrudeMesh/extrudeMesh.C
@@ -60,6 +60,7 @@ Description
 #include "wedgePolyPatch.H"
 #include "planeExtrusion.H"
 #include "emptyPolyPatch.H"
+#include "processorPolyPatch.H"
 #include "processorMeshes.H"
 #include "hexRef8Data.H"
 
diff --git a/applications/utilities/mesh/generation/foamyMesh/conformalVoronoiMesh/conformalVoronoiMesh/conformalVoronoiMeshCalcDualMesh.C b/applications/utilities/mesh/generation/foamyMesh/conformalVoronoiMesh/conformalVoronoiMesh/conformalVoronoiMeshCalcDualMesh.C
index ad2ce6d098..72e91c3100 100644
--- a/applications/utilities/mesh/generation/foamyMesh/conformalVoronoiMesh/conformalVoronoiMesh/conformalVoronoiMeshCalcDualMesh.C
+++ b/applications/utilities/mesh/generation/foamyMesh/conformalVoronoiMesh/conformalVoronoiMesh/conformalVoronoiMeshCalcDualMesh.C
@@ -163,9 +163,8 @@ void Foam::conformalVoronoiMesh::calcTetMesh
 
     label nPatches = patchNames.size();
 
-    List<DynamicList<face>> patchFaces(nPatches, DynamicList<face>(0));
-
-    List<DynamicList<label>> patchOwners(nPatches, DynamicList<label>(0));
+    List<DynamicList<face>> patchFaces(nPatches);
+    List<DynamicList<label>> patchOwners(nPatches);
 
     faces.setSize(number_of_finite_facets());
 
@@ -1711,12 +1710,11 @@ void Foam::conformalVoronoiMesh::createFacesOwnerNeighbourAndPatches
             patchDicts[patchi].getOrDefault<label>("neighbProcNo", -1);
     }
 
-    List<DynamicList<face>> patchFaces(nPatches, DynamicList<face>(0));
-    List<DynamicList<label>> patchOwners(nPatches, DynamicList<label>(0));
+    List<DynamicList<face>> patchFaces(nPatches);
+    List<DynamicList<label>> patchOwners(nPatches);
     // Per patch face the index of the slave node of the point pair
-    List<DynamicList<label>> patchPPSlaves(nPatches, DynamicList<label>(0));
-
-    List<DynamicList<bool>> indirectPatchFace(nPatches, DynamicList<bool>(0));
+    List<DynamicList<label>> patchPPSlaves(nPatches);
+    List<DynamicList<bool>> indirectPatchFace(nPatches);
 
 
     faces.setSize(number_of_finite_edges());
diff --git a/applications/utilities/mesh/generation/snappyHexMesh/snappyHexMesh.C b/applications/utilities/mesh/generation/snappyHexMesh/snappyHexMesh.C
index 1c9e886c28..51d7bde843 100644
--- a/applications/utilities/mesh/generation/snappyHexMesh/snappyHexMesh.C
+++ b/applications/utilities/mesh/generation/snappyHexMesh/snappyHexMesh.C
@@ -55,7 +55,7 @@ Description
 #include "faceSet.H"
 #include "motionSmoother.H"
 #include "polyTopoChange.H"
-#include "uindirectPrimitivePatch.H"
+#include "indirectPrimitivePatch.H"
 #include "surfZoneIdentifierList.H"
 #include "UnsortedMeshedSurface.H"
 #include "MeshedSurface.H"
diff --git a/applications/utilities/mesh/manipulation/createBaffles/createBaffles.C b/applications/utilities/mesh/manipulation/createBaffles/createBaffles.C
index 269317bc3b..ca13af55b9 100644
--- a/applications/utilities/mesh/manipulation/createBaffles/createBaffles.C
+++ b/applications/utilities/mesh/manipulation/createBaffles/createBaffles.C
@@ -57,6 +57,7 @@ Description
 
 #include "fvMeshTools.H"
 #include "topoSet.H"
+#include "processorPolyPatch.H"
 #include "processorMeshes.H"
 
 using namespace Foam;
diff --git a/applications/utilities/mesh/manipulation/splitMesh/splitMesh.C b/applications/utilities/mesh/manipulation/splitMesh/splitMesh.C
index 705cf82052..4fdd5c2264 100644
--- a/applications/utilities/mesh/manipulation/splitMesh/splitMesh.C
+++ b/applications/utilities/mesh/manipulation/splitMesh/splitMesh.C
@@ -58,7 +58,7 @@ Description
 #include "attachDetach.H"
 #include "attachPolyTopoChanger.H"
 #include "regionSide.H"
-#include "primitiveFacePatch.H"
+#include "primitivePatch.H"
 #include "processorMeshes.H"
 
 using namespace Foam;
diff --git a/applications/utilities/postProcessing/dataConversion/foamToVTK/writeAreaFields.H b/applications/utilities/postProcessing/dataConversion/foamToVTK/writeAreaFields.H
index 958c56954d..d8111f5f7a 100644
--- a/applications/utilities/postProcessing/dataConversion/foamToVTK/writeAreaFields.H
+++ b/applications/utilities/postProcessing/dataConversion/foamToVTK/writeAreaFields.H
@@ -39,7 +39,7 @@ SourceFiles
 #define writeAreaFields_H
 
 #include "readFields.H"
-#include "foamVtkUIndPatchGeoFieldsWriter.H"
+#include "foamVtkIndPatchGeoFieldsWriter.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
diff --git a/applications/utilities/postProcessing/dataConversion/foamToVTK/writeSurfaceFields.H b/applications/utilities/postProcessing/dataConversion/foamToVTK/writeSurfaceFields.H
index b41ce0a889..530ffd2d28 100644
--- a/applications/utilities/postProcessing/dataConversion/foamToVTK/writeSurfaceFields.H
+++ b/applications/utilities/postProcessing/dataConversion/foamToVTK/writeSurfaceFields.H
@@ -38,7 +38,7 @@ SourceFiles
 #define writeSurfaceFields_H
 
 #include "readFields.H"
-#include "primitiveFacePatch.H"
+#include "primitivePatch.H"
 #include "foamVtkGenericPatchGeoFieldsWriter.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
diff --git a/applications/utilities/preProcessing/viewFactorsGen/viewFactorsGen.C b/applications/utilities/preProcessing/viewFactorsGen/viewFactorsGen.C
index 14d4534b1b..a32b878ec9 100644
--- a/applications/utilities/preProcessing/viewFactorsGen/viewFactorsGen.C
+++ b/applications/utilities/preProcessing/viewFactorsGen/viewFactorsGen.C
@@ -57,7 +57,7 @@ Description
 #include "distributedTriSurfaceMesh.H"
 #include "meshTools.H"
 
-#include "uindirectPrimitivePatch.H"
+#include "indirectPrimitivePatch.H"
 #include "DynamicField.H"
 #include "unitConversion.H"
 
diff --git a/applications/utilities/surface/surfaceMeshExtract/surfaceMeshExtract.C b/applications/utilities/surface/surfaceMeshExtract/surfaceMeshExtract.C
index a8b386cb7a..67caa47ee9 100644
--- a/applications/utilities/surface/surfaceMeshExtract/surfaceMeshExtract.C
+++ b/applications/utilities/surface/surfaceMeshExtract/surfaceMeshExtract.C
@@ -51,7 +51,7 @@ Description
 #include "emptyPolyPatch.H"
 #include "processorPolyPatch.H"
 #include "ListListOps.H"
-#include "uindirectPrimitivePatch.H"
+#include "indirectPrimitivePatch.H"
 #include "globalMeshData.H"
 #include "globalIndex.H"
 #include "timeSelector.H"
diff --git a/src/OSspecific/MSwindows/signals/sigFpe.C b/src/OSspecific/MSwindows/signals/sigFpe.C
index 0a06c4c30a..98550ac67f 100644
--- a/src/OSspecific/MSwindows/signals/sigFpe.C
+++ b/src/OSspecific/MSwindows/signals/sigFpe.C
@@ -32,8 +32,8 @@ License
 #include "JobInfo.H"
 #include "OSspecific.H"
 #include "IOstreams.H"
+#include "List.H"
 #include "Switch.H"
-#include "UList.H"
 
 #include <float.h>  // For *fp functions
 #include <limits>
diff --git a/src/OSspecific/POSIX/signals/sigFpe.C b/src/OSspecific/POSIX/signals/sigFpe.C
index 110fff0131..c02588e19b 100644
--- a/src/OSspecific/POSIX/signals/sigFpe.C
+++ b/src/OSspecific/POSIX/signals/sigFpe.C
@@ -31,8 +31,8 @@ License
 #include "JobInfo.H"
 #include "OSspecific.H"
 #include "IOstreams.H"
+#include "List.H"
 #include "Switch.H"
-#include "UList.H"
 
 #include <limits>
 
diff --git a/src/OpenFOAM/Make/files b/src/OpenFOAM/Make/files
index edd6b51add..ab3eea8736 100644
--- a/src/OpenFOAM/Make/files
+++ b/src/OpenFOAM/Make/files
@@ -317,7 +317,7 @@ $(IOdictionary)/localIOdictionary.C
 $(IOdictionary)/unwatchedIOdictionary.C
 $(IOdictionary)/IOdictionary.C
 
-db/IOobjects/IOMap/IOMapName.C
+db/IOobjects/IOMap/IOMaps.C
 db/IOobjects/decomposedBlockData/decomposedBlockData.C
 db/IOobjects/decomposedBlockData/decomposedBlockDataHeader.C
 db/IOobjects/GlobalIOField/GlobalIOFields.C
diff --git a/src/OpenFOAM/containers/Bits/PackedList/PackedList.H b/src/OpenFOAM/containers/Bits/PackedList/PackedList.H
index 1cb1395ad2..9b281f158f 100644
--- a/src/OpenFOAM/containers/Bits/PackedList/PackedList.H
+++ b/src/OpenFOAM/containers/Bits/PackedList/PackedList.H
@@ -344,7 +344,7 @@ public:
         //- a minimum position, below which trimming will not occur.
         //
         //  \return true if trimming changed the size.
-        inline bool trim(label minpos=-1);
+        inline bool trim(label minpos = -1);
 
         //- Clear all bits but do not adjust the addressable size.
         //  \note Method name compatibility with boost::dynamic_bitset
diff --git a/src/OpenFOAM/containers/Bits/bitSet/bitSet.C b/src/OpenFOAM/containers/Bits/bitSet/bitSet.C
index 2a778de499..1e7ad6fcf5 100644
--- a/src/OpenFOAM/containers/Bits/bitSet/bitSet.C
+++ b/src/OpenFOAM/containers/Bits/bitSet/bitSet.C
@@ -43,7 +43,7 @@ Foam::bitSet& Foam::bitSet::minusEq(const bitSet& other)
 {
     if (&other == this)
     {
-        // Self '-=' : results in clearing all bits
+        // Self '-=' : clears all bits
         if (debug & 2)
         {
             InfoInFunction
@@ -53,12 +53,12 @@ Foam::bitSet& Foam::bitSet::minusEq(const bitSet& other)
         reset();
         return *this;
     }
-    else if (empty() || other.empty())
+    else if (none() || other.none())
     {
+        // no-op: nothing can change
         return *this;
     }
 
-
     // The operation (on overlapping blocks)
     {
         const label nblocks = num_blocks(std::min(size(), other.size()));
@@ -88,21 +88,32 @@ Foam::bitSet& Foam::bitSet::andEq(const bitSet& other)
 
         return *this;
     }
-    else if (empty())
+    else if (none())
     {
-        // empty set : no-op (no overlap possible)
+        // no-op: nothing is set - no intersection possible
         return *this;
     }
-    else if (other.empty())
+    else if (other.none())
     {
-        reset();  // Other is empty - no overlap possible
+        // no-op: other has nothing set - no intersection possible
+        reset();
         return *this;
     }
 
 
+    const label origSize(size());
+    const label otherSize(other.size());
+
+    if (origSize > otherSize)
+    {
+        // Clear bits (and blocks) that do not overlap at all
+        resize(otherSize);
+        resize(origSize);
+    }
+
     // The operation (on overlapping blocks)
     {
-        const label nblocks = num_blocks(std::min(size(), other.size()));
+        const label nblocks = num_blocks(std::min(origSize, otherSize));
         const auto& rhs = other.blocks_;
 
         for (label blocki = 0; blocki < nblocks; ++blocki)
@@ -115,7 +126,7 @@ Foam::bitSet& Foam::bitSet::andEq(const bitSet& other)
 }
 
 
-Foam::bitSet& Foam::bitSet::orEq(const bitSet& other, const bool strict)
+Foam::bitSet& Foam::bitSet::orEq(const bitSet& other)
 {
     if (&other == this)
     {
@@ -129,52 +140,21 @@ Foam::bitSet& Foam::bitSet::orEq(const bitSet& other, const bool strict)
 
         return *this;
     }
-    else if (other.empty())
+    else if (other.none())
     {
-        if ((debug & 2) && !empty())
-        {
-            // OK if both are empty
-            InfoInFunction
-                << "Perform |= using empty operand: ignore" << nl;
-        }
-
-        // No (normal) overlap: no-op
+        // no-op: nothing can change
         return *this;
     }
-    else if (empty())
+
+
+    // Largest new bit that could be introduced
+    const label otherMax(other.find_last());
+
+    if (otherMax >= size())
     {
-        if (debug & 2)
-        {
-            InfoInFunction
-                << "Perform |= on empty bitSet" << nl;
-        }
-
-        if (strict)
-        {
-            // No (normal) overlap: no-op
-            return *this;
-        }
+        // Extend to accommodate bits from 'other'
+        resize(otherMax+1);
     }
-    else if ((debug & 2) && (size() != other.size()))
-    {
-        InfoInFunction
-            << "Perform |= on dissimilar sized bitSets: "
-            << size()  << " vs. " << other.size() << nl;
-    }
-
-    label minpos = -1; // Min trim point
-
-    if ((size() < other.size()) && !strict)
-    {
-        // The size (B > A) and we are non-strict (greedy), which means we may
-        // acquire additional bits from B. However, we would like to avoid
-        // spurious changes in the size of A (ie, B is longer but the extra
-        // bits are unset and thus don't affect the logical result).
-
-        minpos = size();
-        resize(other.size());   // Blocks now overlap
-    }
-
 
     // The operation (on overlapping blocks)
     {
@@ -187,26 +167,15 @@ Foam::bitSet& Foam::bitSet::orEq(const bitSet& other, const bool strict)
         }
     }
 
-
-    // Cleanup - minpos >= 0 means we need to check/adjust the trim point
-    if (minpos >= 0)
-    {
-        trim(minpos); // Adjust the trim point (size)
-    }
-    else
-    {
-        clear_trailing_bits();
-    }
-
     return *this;
 }
 
 
-Foam::bitSet& Foam::bitSet::xorEq(const bitSet& other, const bool strict)
+Foam::bitSet& Foam::bitSet::xorEq(const bitSet& other)
 {
     if (&other == this)
     {
-        // Self '^=' : results in clearing all bits
+        // Self '^=' : clears all bits
 
         if (debug & 2)
         {
@@ -217,47 +186,21 @@ Foam::bitSet& Foam::bitSet::xorEq(const bitSet& other, const bool strict)
         reset();
         return *this;
     }
-    else if (other.empty())
+    else if (other.none())
     {
-        if ((debug & 2) && !empty())
-        {
-            // OK if both are empty
-            InfoInFunction
-                << "Perform ^= using empty operand: ignore" << nl;
-        }
-
-        // No (normal) overlap: no-op
+        // no-op: nothing can change
         return *this;
     }
-    else if (empty())
+
+
+    // Largest new bit that could be introduced
+    const label otherMax(other.find_last());
+
+    if (otherMax >= size())
     {
-        if (debug & 2)
-        {
-            InfoInFunction
-                << "Perform ^= on empty bitSet" << nl;
-        }
-
-        if (strict)
-        {
-            // No (normal) overlap: no-op
-            return *this;
-        }
+        // Extend to accommodate bits from 'other'
+        resize(otherMax+1);
     }
-    else if ((debug & 2) && (size() != other.size()))
-    {
-        InfoInFunction
-            << "Perform ^= on dissimilar sized bitSets: "
-            << size()  << " vs. " << other.size() << nl;
-    }
-
-    label minpos = -1; // Min trim point
-
-    if ((size() < other.size()) && !strict)
-    {
-        minpos = size();        // This logic is explained in the orEq() method
-        resize(other.size());   // Blocks now overlap
-    }
-
 
     // The operation (on overlapping blocks)
     {
@@ -270,17 +213,6 @@ Foam::bitSet& Foam::bitSet::xorEq(const bitSet& other, const bool strict)
         }
     }
 
-
-    // Cleanup - minpos >= 0 means we need to check/adjust the trim point
-    if (minpos >= 0)
-    {
-        trim(minpos); // Adjust the trim point (size)
-    }
-    else
-    {
-        clear_trailing_bits();
-    }
-
     return *this;
 }
 
diff --git a/src/OpenFOAM/containers/Bits/bitSet/bitSet.H b/src/OpenFOAM/containers/Bits/bitSet/bitSet.H
index 1bcafd563b..1ed379e172 100644
--- a/src/OpenFOAM/containers/Bits/bitSet/bitSet.H
+++ b/src/OpenFOAM/containers/Bits/bitSet/bitSet.H
@@ -83,7 +83,8 @@ protected:
         //      A = (A & ~B)
         //  \endcode
         //  A and B can have different sizes.
-        //  Does not change the original set size.
+        //  Never changes the original set size.
+        //  Non-overlapping parts are considered \em off.
         bitSet& minusEq(const bitSet& other);
 
         //- The set logical AND
@@ -91,8 +92,9 @@ protected:
         //      A = (A & B)
         //
         //  \endcode
-        //  A and B can have different sizes..
-        //  Does not change the original set size.
+        //  A and B can have different sizes.
+        //  Never changes the original set size.
+        //  Non-overlapping parts are considered \em off.
         bitSet& andEq(const bitSet& other);
 
         //- The set logical OR
@@ -101,18 +103,17 @@ protected:
         //  \endcode
         //  A and B can have different sizes
         //
-        //  \note
-        //      The default (strict=true) ignores additional length from B,
-        //      whereas (strict=false) permits the set to automatically grow
-        //      to accommodate additional elements arising from B.
-        bitSet& orEq(const bitSet& other, const bool strict=true);
+        //  The size grows to accommodate new \em on bits.
+        bitSet& orEq(const bitSet& other);
 
         //- The set logical XOR
         //  \code
         //      A = (A ^ B)
         //  \endcode
-        //  A and B can have different sizes. Sizing behaviour as per orEq.
-        bitSet& xorEq(const bitSet& other, const bool strict=true);
+        //  A and B can have different sizes.
+        //
+        //  The size grows to accommodate new \em on bits.
+        bitSet& xorEq(const bitSet& other);
 
 
 public:
@@ -123,6 +124,7 @@ public:
         class const_iterator;
         typedef unsigned int const_reference;
 
+
     // Static Member Functions
 
         //- Return a null bitSet reference
@@ -363,10 +365,14 @@ public:
         //- Invert all bits in the addressable region
         inline void flip();
 
-        //- Invert bits at the specified position.
+        //- Invert bit at the specified position.
         //  A no-op if the position is out-of-range
         inline void flip(const label pos);
 
+        //- Resize to include the last \em on bit only.
+        //  Functionally identical to resize(find_last()+1)
+        inline void resize_last();
+
         //- Swap contents
         inline void swap(bitSet& bitset);
 
@@ -573,23 +579,24 @@ public:
         inline bitSet& operator=(const bool val);
 
         //- Bitwise-AND all the bits in other with the bits in this bitset.
-        //  The operands may have dissimilar sizes without affecting the size
-        //  of the set.
+        //  The operands may have dissimilar sizes,
+        //  never changes the original set size.
+        //  Non-overlapping elements are considered \em off.
         inline bitSet& operator&=(const bitSet& other);
 
         //- Bitwise-OR operator - similar to the set() method.
-        //  The operands may have dissimilar sizes without affecting the size
-        //  of the set.
+        //  The operands may have dissimilar sizes,
+        //  the set grows to accommodate new \em on bits.
         inline bitSet& operator|=(const bitSet& other);
 
         //- Bitwise-XOR operator - retains unique entries.
-        //  The operands may have dissimilar sizes without affecting the size
-        //  of the set.
+        //  The operands may have dissimilar sizes,
+        //  the set grows to accommodate new \em on bits.
         inline bitSet& operator^=(const bitSet& other);
 
         //- Remove entries from this list - identical to the unset() method.
-        //  The operands may have dissimilar sizes without affecting the size
-        //  of the set.
+        //  The operands may have dissimilar sizes,
+        //  never changes the original set size.
         inline bitSet& operator-=(const bitSet& other);
 
 
diff --git a/src/OpenFOAM/containers/Bits/bitSet/bitSetI.H b/src/OpenFOAM/containers/Bits/bitSet/bitSetI.H
index 1ad6e80a80..a32f68db8b 100644
--- a/src/OpenFOAM/containers/Bits/bitSet/bitSetI.H
+++ b/src/OpenFOAM/containers/Bits/bitSet/bitSetI.H
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2018-2020 OpenCFD Ltd.
+    Copyright (C) 2018-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -316,6 +316,7 @@ inline Foam::label Foam::bitSet::find_first() const
     // Process block-wise, detecting any '1' bits
 
     const label nblocks = num_blocks(size());
+
     for (label blocki = 0; blocki < nblocks; ++blocki)
     {
         label pos = (blocki * elem_per_block);
@@ -535,6 +536,21 @@ inline Foam::labelList Foam::bitSet::sortedToc() const
 }
 
 
+inline void Foam::bitSet::resize_last()
+{
+    const label pos = find_last();
+
+    if (pos >= 0)
+    {
+        resize(pos+1);
+    }
+    else
+    {
+        clear();
+    }
+}
+
+
 inline void Foam::bitSet::swap(bitSet& bitset)
 {
     PackedList<1>::swap(bitset);
@@ -573,7 +589,7 @@ inline void Foam::bitSet::fill(const bool val)
 
 inline void Foam::bitSet::set(const bitSet& bitset)
 {
-    orEq(bitset, false);  // Non-strict: Lets the set size grow.
+    orEq(bitset);
 }
 
 
@@ -754,28 +770,40 @@ inline Foam::bitSet Foam::operator~(const bitSet& bitset)
 inline Foam::bitSet Foam::operator&(const bitSet& a, const bitSet& b)
 {
     bitSet result(a);
-    return (result &= b);
+    result &= b;
+
+    result.resize_last();
+    return result;
 }
 
 
 inline Foam::bitSet Foam::operator|(const bitSet& a, const bitSet& b)
 {
     bitSet result(a);
-    return (result |= b);
+    result |= b;
+
+    result.resize_last();
+    return result;
 }
 
 
 inline Foam::bitSet Foam::operator^(const bitSet& a, const bitSet& b)
 {
     bitSet result(a);
-    return (result ^= b);
+    result ^= b;
+
+    result.resize_last();
+    return result;
 }
 
 
 inline Foam::bitSet Foam::operator-(const bitSet& a, const bitSet& b)
 {
     bitSet result(a);
-    return (result -= b);
+    result |= b;
+
+    result.resize_last();
+    return result;
 }
 
 
diff --git a/src/OpenFOAM/containers/HashTables/HashTable/HashTable.C b/src/OpenFOAM/containers/HashTables/HashTable/HashTable.C
index c4801b8c80..fac18c0c67 100644
--- a/src/OpenFOAM/containers/HashTables/HashTable/HashTable.C
+++ b/src/OpenFOAM/containers/HashTables/HashTable/HashTable.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2017-2021 OpenCFD Ltd.
+    Copyright (C) 2017-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -26,12 +26,13 @@ License
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef HashTable_C
-#define HashTable_C
+#ifndef Foam_HashTable_C
+#define Foam_HashTable_C
 
 #include "HashTable.H"
 #include "List.H"
 #include "FixedList.H"
+#include "UPtrList.H"
 
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
@@ -156,6 +157,45 @@ Foam::List<Key> Foam::HashTable<T, Key, Hash>::sortedToc
 }
 
 
+template<class T, class Key, class Hash>
+Foam::UPtrList<const typename Foam::HashTable<T, Key, Hash>::node_type>
+Foam::HashTable<T, Key, Hash>::sorted() const
+{
+    UPtrList<const node_type> list(size_);
+
+    label count = 0;
+
+    for (const_iterator iter = cbegin(); iter != cend(); ++iter)
+    {
+        list.set(count++, iter.node());
+    }
+
+    Foam::sort(list);
+
+    return list;
+}
+
+
+template<class T, class Key, class Hash>
+Foam::UPtrList<typename Foam::HashTable<T, Key, Hash>::node_type>
+Foam::HashTable<T, Key, Hash>::sorted()
+{
+    UPtrList<node_type> list(size_);
+
+    label count = 0;
+
+    for (iterator iter = begin(); iter != end(); ++iter)
+    {
+        list.set(count++, iter.node());
+    }
+
+    Foam::sort(list);
+
+    return list;
+}
+
+
+
 template<class T, class Key, class Hash>
 template<class UnaryPredicate>
 Foam::List<Key> Foam::HashTable<T, Key, Hash>::tocKeys
diff --git a/src/OpenFOAM/containers/HashTables/HashTable/HashTable.H b/src/OpenFOAM/containers/HashTables/HashTable/HashTable.H
index 7296b8c18d..cbcdd84179 100644
--- a/src/OpenFOAM/containers/HashTables/HashTable/HashTable.H
+++ b/src/OpenFOAM/containers/HashTables/HashTable/HashTable.H
@@ -34,7 +34,8 @@ Description
     depends on the method used to generate the hash key index, the
     table capacity, insertion order etc. When the key order is
     important, use the sortedToc() method to obtain a list of sorted
-    keys and use that for further access.
+    keys and use that for further access, or the sorted() method
+    to obtain a UPtrList of entries to traverse in sorted order.
 
     Internally the table uses closed addressing into a flat storage space
     with collisions handled by linked-list chaining.
@@ -80,8 +81,8 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef HashTable_H
-#define HashTable_H
+#ifndef Foam_HashTable_H
+#define Foam_HashTable_H
 
 #include "word.H"
 #include "zero.H"
@@ -102,6 +103,7 @@ namespace Foam
 
 template<class T> class List;
 template<class T> class UList;
+template<class T> class UPtrList;
 template<class T, unsigned N> class FixedList;
 template<class T, class Key, class Hash> class HashTable;
 
@@ -120,9 +122,15 @@ class HashTable
 :
     public HashTableCore
 {
-    // Types
+public:
 
-        //- Table entry. A hashed node with a linked-list for collisions
+    // Data Types
+
+        //- The template instance used for this HashTable
+        typedef HashTable<T, Key, Hash> this_type;
+
+        //- A table entry (node) that encapsulates the key/val tuple
+        //- with an additional linked-list entry for hash collisions
         typedef typename std::conditional
         <
             std::is_same<zero::null, typename std::remove_cv<T>::type>::value,
@@ -131,42 +139,6 @@ class HashTable
         >::type node_type;
 
 
-    // Private Data
-
-        //- The number of nodes currently stored in table
-        label size_;
-
-        //- Number of nodes allocated in table
-        label capacity_;
-
-        //- The table of primary nodes
-        node_type** table_;
-
-
-    // Private Member Functions
-
-        //- Return the hash index of the Key within the current table size.
-        //  No checks for zero-sized tables.
-        inline label hashKeyIndex(const Key& key) const;
-
-        //- Assign a new hash-entry to a possibly already existing key.
-        //  \return True if the new entry was set.
-        template<class... Args>
-        bool setEntry(const bool overwrite, const Key& key, Args&&... args);
-
-        //- Read hash table
-        Istream& readTable(Istream& is);
-
-        //- Write hash table
-        Ostream& writeTable(Ostream& os) const;
-
-
-public:
-
-    //- The template instance used for this HashTable
-    typedef HashTable<T, Key, Hash> this_type;
-
-
     // STL type definitions
 
         //- The second template parameter, type of keys used.
@@ -209,6 +181,39 @@ public:
         //- Forward iterator with const access
         class const_iterator;
 
+
+private:
+
+    // Private Data
+
+        //- The number of nodes currently stored in table
+        label size_;
+
+        //- Number of nodes allocated in table
+        label capacity_;
+
+        //- The table of primary nodes
+        node_type** table_;
+
+
+    // Private Member Functions
+
+        //- Return the hash index of the Key within the current table size.
+        //  No checks for zero-sized tables.
+        inline label hashKeyIndex(const Key& key) const;
+
+        //- Assign a new hash-entry to a possibly already existing key.
+        //  \return True if the new entry was set.
+        template<class... Args>
+        bool setEntry(const bool overwrite, const Key& key, Args&&... args);
+
+        //- Read hash table
+        Istream& readTable(Istream& is);
+
+        //- Write hash table
+        Ostream& writeTable(Ostream& os) const;
+
+
 protected:
 
         //- Internally used base for iterator and const_iterator
@@ -220,6 +225,7 @@ protected:
         //- An iterator with non-const access to HashTable internals.
         friend class Iterator<false>;
 
+
 public:
 
     // Constructors
@@ -336,6 +342,17 @@ public:
         ) const;
 
 
+    // Sorted entries
+
+        //- Const access to the hash-table contents in sorted order
+        //- (sorted by keys).
+        UPtrList<const node_type> sorted() const;
+
+        //- Non-const access to the hash-table contents in sorted order
+        //- (sorted by keys).
+        UPtrList<node_type> sorted();
+
+
     // Counting
 
         //- Count the number of keys that satisfy the unary predicate
@@ -701,6 +718,7 @@ public:
             using iterator_category = std::forward_iterator_tag;
             using difference_type   = this_type::difference_type;
 
+            using node_type   = this_type::node_type;
             using key_type    = this_type::key_type;
             using mapped_type = this_type::mapped_type;
             using value_type  = this_type::value_type;
@@ -724,25 +742,37 @@ public:
 
         // Member Functions/Operators
 
+            //- Const access to the entry (node)
+            const node_type* node() const noexcept
+            {
+                return Iterator<false>::entry_;
+            }
+
+            //- Non-const access to the entry (node)
+            node_type* node() noexcept
+            {
+                return Iterator<false>::entry_;
+            }
+
             //- Const access to referenced object (value)
-            inline const_reference val() const
+            const_reference val() const
             {
                 return Iterator<false>::entry_->cval();
             }
 
             //- Non-const access to referenced object (value)
-            inline reference val()
+            reference val()
             {
                 return Iterator<false>::entry_->val();
             }
 
             //- Const access to referenced object (value)
-            inline const_reference operator*() const  { return this->val(); }
-            inline const_reference operator()() const { return this->val(); }
+            const_reference operator*() const  { return this->val(); }
+            const_reference operator()() const { return this->val(); }
 
             //- Non-const access to referenced object (value)
-            inline reference operator*()  { return this->val(); }
-            inline reference operator()() { return this->val(); }
+            reference operator*()  { return this->val(); }
+            reference operator()() { return this->val(); }
 
             inline iterator& operator++();
             inline iterator operator++(int);
@@ -762,6 +792,7 @@ public:
             using iterator_category = std::forward_iterator_tag;
             using difference_type   = this_type::difference_type;
 
+            using node_type   = this_type::node_type;
             using key_type    = this_type::key_type;
             using mapped_type = const this_type::mapped_type;
             using value_type  = const this_type::value_type;
@@ -799,15 +830,21 @@ public:
 
         // Member Functions/Operators
 
+            //- Const access to the entry (node)
+            const node_type* node() const noexcept
+            {
+                return Iterator<true>::entry_;
+            }
+
             //- Const access to referenced object (value)
-            inline reference val() const
+            reference val() const
             {
                 return Iterator<true>::entry_->cval();
             }
 
             //- Const access to referenced object (value)
-            inline reference operator*() const  { return this->val(); }
-            inline reference operator()() const { return this->val(); }
+            reference operator*() const  { return this->val(); }
+            reference operator()() const { return this->val(); }
 
             inline const_iterator& operator++();
             inline const_iterator operator++(int);
@@ -853,8 +890,8 @@ public:
             {}
 
             //- Return the key
-            inline reference operator*() const  { return this->key(); }
-            inline reference operator()() const { return this->key(); }
+            reference operator*() const  { return this->key(); }
+            reference operator()() const { return this->key(); }
 
             inline key_iterator_base& operator++()
             {
diff --git a/src/OpenFOAM/containers/HashTables/HashTable/HashTableDetail.H b/src/OpenFOAM/containers/HashTables/HashTable/HashTableDetail.H
index 5272915538..dadd621297 100644
--- a/src/OpenFOAM/containers/HashTables/HashTable/HashTableDetail.H
+++ b/src/OpenFOAM/containers/HashTables/HashTable/HashTableDetail.H
@@ -34,8 +34,8 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef HashTableDetail_H
-#define HashTableDetail_H
+#ifndef Foam_HashTableDetail_H
+#define Foam_HashTableDetail_H
 
 #include "zero.H"
 #include <memory>
@@ -73,13 +73,13 @@ template<class T> struct isPointerLike<std::unique_ptr<T>> : std::true_type {};
 \*---------------------------------------------------------------------------*/
 
 //- Internal storage type for HashTable entries
-//  Structure with a (K,V) tuple and a linked-list for collisions
+//  Comprises a (K,V) tuple and a linked-list entry for hash collisions.
 //  Could store key/val as std::pair, but no particular advantage
 //  unless the iterator dereference type changes.
 template<class K, class V>
 struct HashTablePair
 {
-    // Types
+    // Data Types
 
         //- Type of key
         typedef K key_type;
@@ -87,26 +87,26 @@ struct HashTablePair
         //- Type of content
         typedef V mapped_type;
 
-        //- This struct stores a value
+        //- This class stores a value
         static constexpr bool stores_value() noexcept
         {
             return true;
         }
 
 
-    // Member Data
+    // Data
 
         //- The lookup key
-        key_type key_;
+        const K key_;
 
         //- The mapped data
-        mapped_type val_;
+        V val_;
 
         //- Addressing (next in collision list)
         HashTablePair* next_;
 
 
-    // Member Functions
+    // Generated Methods
 
         //- No copy construct
         HashTablePair(const HashTablePair&) = delete;
@@ -115,6 +115,8 @@ struct HashTablePair
         void operator=(const HashTablePair&) = delete;
 
 
+    // Constructors
+
         //- Construct from next pointer, key, contents
         template<class... Args>
         HashTablePair
@@ -130,24 +132,39 @@ struct HashTablePair
         {}
 
 
+    // Member Functions
+
         //- The key
-        const key_type& key() const
+        const key_type& key() const noexcept
         {
             return key_;
         }
 
         //- Const access to the mapped value
-        const mapped_type& cval() const
+        const mapped_type& cval() const noexcept
+        {
+            return val_;
+        }
+
+        //- Const access to the mapped value
+        const mapped_type& val() const noexcept
         {
             return val_;
         }
 
         //- Non-const access to the mapped value
-        mapped_type& val()
+        mapped_type& val() noexcept
         {
             return val_;
         }
 
+
+        //- Compare keys
+        bool operator<(const HashTablePair& rhs) const
+        {
+            return key_ < rhs.key_;
+        }
+
         //- Write (key, val) pair - for pointer types
         template<class TypeT = V>
         typename std::enable_if
@@ -190,38 +207,38 @@ struct HashTablePair
 \*---------------------------------------------------------------------------*/
 
 //- Internal storage type for HashSet entries
-//  Structure with a single (K) value and a linked-list for collisions
+//  Comprises a single (K) value and a linked-list entry for hash collisions
 template<class K>
 struct HashTableSingle
 {
-    // Types
+    // Data Types
 
         //- Type of key
         typedef K key_type;
 
-        //- Type of content
+        //- Type of content (no content: placeholder)
         typedef Foam::zero::null mapped_type;
 
         //- Content storage type to the entry
         typedef key_type value_type;
 
-        //- This struct does not store a value
+        //- This class does not store any value
         static constexpr bool stores_value() noexcept
         {
             return false;
         }
 
 
-    // Member Data
+    // Data
 
         //- The lookup key == content
-        key_type key_;
+        const K key_;
 
         //- Addressing (next in collision list)
         HashTableSingle* next_;
 
 
-    // Member Functions
+    // Generated Methods
 
         //- No copy construct
         HashTableSingle(const HashTableSingle&) = delete;
@@ -230,6 +247,8 @@ struct HashTableSingle
         void operator=(const HashTableSingle&) = delete;
 
 
+    // Constructors
+
         //- Construct from next pointer, key, (unused) contents
         template<class... Args>
         HashTableSingle
@@ -244,25 +263,40 @@ struct HashTableSingle
         {}
 
 
+    // Member Functions
+
         //- The key
-        const key_type& key() const
+        const key_type& key() const noexcept
         {
             return key_;
         }
 
         //- Const access to the (dummy) mapped value
-        const mapped_type& cval() const
+        const mapped_type& cval() const noexcept
+        {
+            return Foam::zero::null::dummy;
+        }
+
+        //- Const access to the (dummy) mapped value
+        const mapped_type& val() const noexcept
         {
             return Foam::zero::null::dummy;
         }
 
         //- Non-const access to the (dummy) mapped value
-        mapped_type& val()
+        mapped_type& val() noexcept
         {
             return Foam::zero::null::dummy;
         }
 
-        //- Write the key. There is no value
+
+        //- Compare keys
+        bool operator<(const HashTableSingle& rhs) const
+        {
+            return key_ < rhs.key_;
+        }
+
+        //- Write the key. There is no value to write.
         void print(Ostream& os) const
         {
             os << key_;
diff --git a/src/OpenFOAM/containers/IndirectLists/IndirectList/IndirectList.H b/src/OpenFOAM/containers/IndirectLists/IndirectList/IndirectList.H
index 63c43d4792..5e802a6b57 100644
--- a/src/OpenFOAM/containers/IndirectLists/IndirectList/IndirectList.H
+++ b/src/OpenFOAM/containers/IndirectLists/IndirectList/IndirectList.H
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2017-2019 OpenCFD Ltd.
+    Copyright (C) 2017-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -33,22 +33,82 @@ Description
 See also
     Foam::UIndirectList for a version without addressing allocation.
 
+Class
+    Foam::UIndirectList
+
+Description
+    A List with indirect addressing.
+    Like IndirectList but does not store addressing
+
+    Note the const_cast of the list values. This is so we can use it both
+    on const and non-const lists. Alternative would be to have a const_
+    variant etc.
+
 SourceFiles
     IndirectListI.H
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef IndirectList_H
-#define IndirectList_H
+#ifndef Foam_IndirectList_H
+#define Foam_IndirectList_H
 
+#include "List.H"
+#include "IndirectListBase.H"
 #include "IndirectListAddressing.H"
-#include "UIndirectList.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 namespace Foam
 {
 
+// Forward Declarations
+template<class T> class IndirectList;
+template<class T> class UIndirectList;
+
+// Common list types
+typedef UIndirectList<bool> boolUIndList;       //!< UIndirectList of bools
+typedef UIndirectList<label> labelUIndList;     //!< UIndirectList of labels
+
+
+/*---------------------------------------------------------------------------*\
+                        Class UIndirectList Declaration
+\*---------------------------------------------------------------------------*/
+
+template<class T>
+class UIndirectList
+:
+    public IndirectListBase<T, labelUList>
+{
+public:
+
+    // Constructors
+
+        //- Shallow copy values and addressing
+        UIndirectList(const UList<T>& values, const labelUList& addr)
+        :
+            IndirectListBase<T, labelUList>(values, addr)
+        {}
+
+        //- Copy construct (shallow copy values and addressing)
+        UIndirectList(const UIndirectList<T>& list)
+        :
+            UIndirectList<T>(list.values(), list.addressing())
+        {}
+
+
+    // Member Operators
+
+        //- Use standard assignment operations
+        using IndirectListBase<T, labelUList>::operator=;
+
+        //- Deep copy values, Fatal if list sizes are not identical
+        void operator=(const UIndirectList<T>& rhs)
+        {
+            this->copyList(rhs);
+        }
+};
+
+
 /*---------------------------------------------------------------------------*\
                         Class IndirectList Declaration
 \*---------------------------------------------------------------------------*/
@@ -82,6 +142,53 @@ public:
         inline explicit IndirectList(const UIndirectList<T>& list);
 
 
+    // Static Functions
+
+        //- Return an IndirectList comprising entries with \em positions
+        //- that satisfy the condition predicate.
+        //
+        //  The condition predicate can be considered a type of \em mask
+        //  for any given position.
+        //  A boolList, bitSet, labelRange or labelHashSet all satisfy
+        //  the requirements for use as position condition predicates.
+        //
+        //  \param values  The source list values
+        //  \param select  Accept/reject predicate based on \em position.
+        //  \param invert  Invert (negate) the selection logic
+        template<class UnaryCondition>
+        static IndirectList<T> subset
+        (
+            const UList<T>& values,
+            const UnaryCondition& select,
+            const bool invert = false
+        );
+
+        //- Return an IndirectList comprising entries with \em values
+        //- that satisfy the predicate.
+        //
+        //  \param values  The source list values
+        //  \param pred    Predicate used to test the \em value
+        //  \param invert  Invert (negate) the selection logic
+        template<class UnaryPredicate>
+        static IndirectList<T> subset_if
+        (
+            const UList<T>& values,
+            const UnaryPredicate& pred,
+            const bool invert = false
+        );
+
+        //- Return an IndirectList with duplicate entries filtered out.
+        //  Preserves the original input order, unless sorted = true
+        //
+        //  \param values  The source list values
+        //  \param sorted  Retain sorted order instead of original order
+        static IndirectList<T> uniq
+        (
+            const UList<T>& values,
+            const bool sorted = false
+        );
+
+
     // Member Functions
 
         //- The list addressing
diff --git a/src/OpenFOAM/containers/IndirectLists/IndirectList/IndirectListI.H b/src/OpenFOAM/containers/IndirectLists/IndirectList/IndirectListI.H
index 76b3415844..eae0ddb4b0 100644
--- a/src/OpenFOAM/containers/IndirectLists/IndirectList/IndirectListI.H
+++ b/src/OpenFOAM/containers/IndirectLists/IndirectList/IndirectListI.H
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2019-2020 OpenCFD Ltd.
+    Copyright (C) 2019-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -115,4 +115,111 @@ inline Foam::IndirectList<T>::IndirectList(const UIndirectList<T>& list)
 {}
 
 
+// * * * * * * * * * * * * * Static Member Functions * * * * * * * * * * * * //
+
+template<class T>
+template<class UnaryCondition>
+Foam::IndirectList<T> Foam::IndirectList<T>::subset
+(
+    const UList<T>& values,
+    const UnaryCondition& select,
+    const bool invert
+)
+{
+    const label len = values.size();
+
+    IndirectList<T> result(values, Foam::zero{});
+    labelList& addr = result.addressing();
+
+    addr.resize_nocopy(len);
+
+    label count = 0;
+    for (label i=0; i < len; ++i)
+    {
+        // Test on position
+        if (select(i) ? !invert : invert)
+        {
+            addr[count] = i;
+            ++count;
+        }
+    }
+    addr.resize(count);
+
+    return result;
+}
+
+
+template<class T>
+template<class UnaryPredicate>
+Foam::IndirectList<T> Foam::IndirectList<T>::subset_if
+(
+    const UList<T>& values,
+    const UnaryPredicate& pred,
+    const bool invert
+)
+{
+    const label len = values.size();
+
+    IndirectList<T> result(values, Foam::zero{});
+    labelList& addr = result.addressing();
+
+    addr.resize_nocopy(len);
+
+    label count = 0;
+    for (label i=0; i < len; ++i)
+    {
+        // Test on value
+        if (pred(values[i]) ? !invert : invert)
+        {
+            addr[count] = i;
+            ++count;
+        }
+    }
+    addr.resize(count);
+
+    return result;
+}
+
+
+template<class T>
+Foam::IndirectList<T> Foam::IndirectList<T>::uniq
+(
+    const UList<T>& values,
+    const bool sorted
+)
+{
+    const label len = values.size();
+
+    IndirectList<T> result(values, Foam::zero{});
+    labelList& order = result.addressing();
+
+    // Start from sorted order
+    Foam::sortedOrder(values, order);
+
+    if (len > 1)
+    {
+        label count = 0;
+        for (label i = 1; i < len; ++i)
+        {
+            // Eliminate duplicates
+            if (values[order[count]] != values[order[i]])
+            {
+                ++count;
+                order[count] = order[i];
+            }
+        }
+        ++count;
+        order.resize(count);
+
+        // Recover the original input order
+        if (!sorted)
+        {
+            Foam::sort(order);
+        }
+    }
+
+    return result;
+}
+
+
 // ************************************************************************* //
diff --git a/src/OpenFOAM/containers/IndirectLists/IndirectList/UIndirectList.H b/src/OpenFOAM/containers/IndirectLists/IndirectList/UIndirectList.H
new file mode 100644
index 0000000000..33e286f573
--- /dev/null
+++ b/src/OpenFOAM/containers/IndirectLists/IndirectList/UIndirectList.H
@@ -0,0 +1,16 @@
+/*---------------------------------------------------------------------------*\
+Description
+    Compatibility include
+
+    UIndirectList.H combined into IndirectList.H (MAY-2022)
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef Foam_UIndirectList_H
+#define Foam_UIndirectList_H
+
+#include "IndirectList.H"
+
+#endif
+
+// ************************************************************************* //
diff --git a/src/OpenFOAM/containers/IndirectLists/IndirectListBase/IndirectListAddressing.H b/src/OpenFOAM/containers/IndirectLists/IndirectListBase/IndirectListAddressing.H
index b760a3d6fc..e7c14bd8f6 100644
--- a/src/OpenFOAM/containers/IndirectLists/IndirectListBase/IndirectListAddressing.H
+++ b/src/OpenFOAM/containers/IndirectLists/IndirectListBase/IndirectListAddressing.H
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2017-2021 OpenCFD Ltd.
+    Copyright (C) 2017-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -33,8 +33,10 @@ Description
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef IndirectListAddressing_H
-#define IndirectListAddressing_H
+#ifndef Foam_IndirectListAddressing_H
+#define Foam_IndirectListAddressing_H
+
+#include <utility>   // std::move
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
diff --git a/src/OpenFOAM/containers/IndirectLists/SortList/SortListI.H b/src/OpenFOAM/containers/IndirectLists/SortList/SortListI.H
index 1d01531742..a60af7c6b7 100644
--- a/src/OpenFOAM/containers/IndirectLists/SortList/SortListI.H
+++ b/src/OpenFOAM/containers/IndirectLists/SortList/SortListI.H
@@ -25,7 +25,7 @@ License
 
 \*---------------------------------------------------------------------------*/
 
-#include "ListOps.H"
+#include "ListOps.H"  // For identity
 
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
diff --git a/src/OpenFOAM/containers/IndirectLists/UIndirectList/UIndirectList.H b/src/OpenFOAM/containers/IndirectLists/UIndirectList/UIndirectList.H
deleted file mode 100644
index 8fc20ac6fe..0000000000
--- a/src/OpenFOAM/containers/IndirectLists/UIndirectList/UIndirectList.H
+++ /dev/null
@@ -1,108 +0,0 @@
-/*---------------------------------------------------------------------------*\
-  =========                 |
-  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
-   \\    /   O peration     |
-    \\  /    A nd           | www.openfoam.com
-     \\/     M anipulation  |
--------------------------------------------------------------------------------
-    Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2017-2019 OpenCFD Ltd.
--------------------------------------------------------------------------------
-License
-    This file is part of OpenFOAM.
-
-    OpenFOAM is free software: you can redistribute it and/or modify it
-    under the terms of the GNU General Public License as published by
-    the Free Software Foundation, either version 3 of the License, or
-    (at your option) any later version.
-
-    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
-    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
-    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
-    for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
-
-Class
-    Foam::UIndirectList
-
-Description
-    A List with indirect addressing.
-
-    Like IndirectList but does not store addressing.
-
-    Note the const_cast of the list values. This is so we can use it both
-    on const and non-const lists. Alternative would be to have a const_
-    variant etc.
-
-SourceFiles
-
-\*---------------------------------------------------------------------------*/
-
-#ifndef UIndirectList_H
-#define UIndirectList_H
-
-#include "List.H"
-#include "IndirectListBase.H"
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-namespace Foam
-{
-
-// Forward Declarations
-template<class T> class UIndirectList;
-
-// Common list types
-typedef UIndirectList<bool> boolUIndList;       //!< UIndirectList of bools
-typedef UIndirectList<label> labelUIndList;     //!< UIndirectList of labels
-
-/*---------------------------------------------------------------------------*\
-                        Class UIndirectList Declaration
-\*---------------------------------------------------------------------------*/
-
-template<class T>
-class UIndirectList
-:
-    public IndirectListBase<T, labelUList>
-{
-public:
-
-    // Constructors
-
-        //- Shallow copy values and addressing
-        UIndirectList(const UList<T>& values, const labelUList& addr)
-        :
-            IndirectListBase<T, labelUList>(values, addr)
-        {}
-
-        //- Copy construct (shallow copy values and addressing)
-        UIndirectList(const UIndirectList<T>& list)
-        :
-            UIndirectList<T>(list.values(), list.addressing())
-        {}
-
-
-    // Member Operators
-
-        //- Use standard assignment operations
-        using IndirectListBase<T, labelUList>::operator=;
-
-        //- Deep copy values, Fatal if list sizes are not identical
-        void operator=(const UIndirectList<T>& rhs)
-        {
-            this->copyList(rhs);
-        }
-};
-
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-} // End namespace Foam
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-#endif
-
-// ************************************************************************* //
diff --git a/src/OpenFOAM/containers/Lists/List/List.C b/src/OpenFOAM/containers/Lists/List/List.C
index 0384aa013c..427218b5f0 100644
--- a/src/OpenFOAM/containers/Lists/List/List.C
+++ b/src/OpenFOAM/containers/Lists/List/List.C
@@ -636,4 +636,52 @@ void Foam::List<T>::operator=(SLList<T>&& list)
 }
 
 
+// * * * * * * * * * * * * * * * Global Functions  * * * * * * * * * * * * * //
+
+template<class T>
+Foam::labelList Foam::sortedOrder
+(
+    const UList<T>& list
+)
+{
+    labelList order;
+    Foam::sortedOrder(list, order, typename UList<T>::less(list));
+    return order;
+}
+
+
+template<class T>
+void Foam::sortedOrder
+(
+    const UList<T>& list,
+    labelList& order
+)
+{
+    Foam::sortedOrder(list, order, typename UList<T>::less(list));
+}
+
+
+template<class T, class ListComparePredicate>
+void Foam::sortedOrder
+(
+    const UList<T>& list,
+    labelList& order,
+    const ListComparePredicate& comp
+)
+{
+    // List lengths must be identical. Old content is overwritten
+    order.resize_nocopy(list.size());
+
+    // Same as std::iota and ListOps::identity
+    label value = 0;
+    for (label& item : order)
+    {
+        item = value;
+        ++value;
+    }
+
+    Foam::stableSort(order, comp);
+}
+
+
 // ************************************************************************* //
diff --git a/src/OpenFOAM/containers/Lists/List/List.H b/src/OpenFOAM/containers/Lists/List/List.H
index 6bf34de25b..8aa6711548 100644
--- a/src/OpenFOAM/containers/Lists/List/List.H
+++ b/src/OpenFOAM/containers/Lists/List/List.H
@@ -373,10 +373,27 @@ Istream& operator>>(Istream& is, List<T>& list)
 
 // * * * * * * * * * * * * * * Global Functions  * * * * * * * * * * * * * * //
 
-//- Create identity map of the given length with (map[i] == i)
+//- Return an identity map of the given length with (map[i] == i)
 //  Optionally with an alternative start index, so that (map[i] == i+start)
 labelList identity(const label len, label start=0);
 
+//- Return the (stable) sort order for the list
+template<class T>
+labelList sortedOrder(const UList<T>& input);
+
+//- Generate the (stable) sort order for the list
+template<class T>
+void sortedOrder(const UList<T>& input, labelList& order);
+
+//- Sort using specified list compare predicate
+template<class T, class ListComparePredicate>
+void sortedOrder
+(
+    const UList<T>& input,
+    labelList& order,
+    const ListComparePredicate& comp
+);
+
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
diff --git a/src/OpenFOAM/containers/Lists/SubList/SubList.H b/src/OpenFOAM/containers/Lists/List/SubList.H
similarity index 98%
rename from src/OpenFOAM/containers/Lists/SubList/SubList.H
rename to src/OpenFOAM/containers/Lists/List/SubList.H
index 6ec68f21b6..d393db4a89 100644
--- a/src/OpenFOAM/containers/Lists/SubList/SubList.H
+++ b/src/OpenFOAM/containers/Lists/List/SubList.H
@@ -39,11 +39,10 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef SubList_H
-#define SubList_H
+#ifndef Foam_SubList_H
+#define Foam_SubList_H
 
 #include "List.H"
-#include "FixedList.H"
 #include "labelRange.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
@@ -52,6 +51,7 @@ namespace Foam
 {
 
 // Forward Declarations
+template<class T, unsigned N> class FixedList;
 template<class T> class SubList;
 
 // Common list types
diff --git a/src/OpenFOAM/containers/Lists/SubList/SubListI.H b/src/OpenFOAM/containers/Lists/List/SubListI.H
similarity index 99%
rename from src/OpenFOAM/containers/Lists/SubList/SubListI.H
rename to src/OpenFOAM/containers/Lists/List/SubListI.H
index e84eb97e91..18718c66f8 100644
--- a/src/OpenFOAM/containers/Lists/SubList/SubListI.H
+++ b/src/OpenFOAM/containers/Lists/List/SubListI.H
@@ -26,6 +26,8 @@ License
 
 \*---------------------------------------------------------------------------*/
 
+#include "FixedList.H"
+
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
 template<class T>
diff --git a/src/OpenFOAM/containers/Lists/UList/UList.C b/src/OpenFOAM/containers/Lists/List/UList.C
similarity index 92%
rename from src/OpenFOAM/containers/Lists/UList/UList.C
rename to src/OpenFOAM/containers/Lists/List/UList.C
index 3c6a3bcf26..6a75e4b6ba 100644
--- a/src/OpenFOAM/containers/Lists/UList/UList.C
+++ b/src/OpenFOAM/containers/Lists/List/UList.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2017-2021 OpenCFD Ltd.
+    Copyright (C) 2017-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -257,41 +257,6 @@ Foam::label Foam::UList<T>::rfind(const T& val, label pos) const
 }
 
 
-template<class T>
-void Foam::sort(UList<T>& a)
-{
-    std::sort(a.begin(), a.end());
-}
-
-
-template<class T, class Compare>
-void Foam::sort(UList<T>& a, const Compare& comp)
-{
-    std::sort(a.begin(), a.end(), comp);
-}
-
-
-template<class T>
-void Foam::stableSort(UList<T>& a)
-{
-    std::stable_sort(a.begin(), a.end());
-}
-
-
-template<class T, class Compare>
-void Foam::stableSort(UList<T>& a, const Compare& comp)
-{
-    std::stable_sort(a.begin(), a.end(), comp);
-}
-
-
-template<class T>
-void Foam::shuffle(UList<T>& a)
-{
-    std::shuffle(a.begin(), a.end(), std::default_random_engine());
-}
-
-
 // * * * * * * * * * * * * * * * Member Operators  * * * * * * * * * * * * * //
 
 template<class T>
@@ -371,4 +336,41 @@ bool Foam::UList<T>::operator>=(const UList<T>& list) const
 }
 
 
+// * * * * * * * * * * * * * * * Global Functions  * * * * * * * * * * * * * //
+
+template<class T>
+void Foam::sort(UList<T>& list)
+{
+    std::sort(list.begin(), list.end());
+}
+
+
+template<class T, class Compare>
+void Foam::sort(UList<T>& list, const Compare& comp)
+{
+    std::sort(list.begin(), list.end(), comp);
+}
+
+
+template<class T>
+void Foam::stableSort(UList<T>& list)
+{
+    std::stable_sort(list.begin(), list.end());
+}
+
+
+template<class T, class Compare>
+void Foam::stableSort(UList<T>& list, const Compare& comp)
+{
+    std::stable_sort(list.begin(), list.end(), comp);
+}
+
+
+template<class T>
+void Foam::shuffle(UList<T>& list)
+{
+    std::shuffle(list.begin(), list.end(), std::default_random_engine());
+}
+
+
 // ************************************************************************* //
diff --git a/src/OpenFOAM/containers/Lists/UList/UList.H b/src/OpenFOAM/containers/Lists/List/UList.H
similarity index 93%
rename from src/OpenFOAM/containers/Lists/UList/UList.H
rename to src/OpenFOAM/containers/Lists/List/UList.H
index b588a264c8..1edd59483e 100644
--- a/src/OpenFOAM/containers/Lists/UList/UList.H
+++ b/src/OpenFOAM/containers/Lists/List/UList.H
@@ -74,6 +74,7 @@ class labelRange;
 template<class T> class List;
 template<class T> class SubList;
 template<class T> class UList;
+template<class T> class IndirectList;
 template<class T, class Addr> class IndirectListBase;
 
 template<class T> Istream& operator>>(Istream&, UList<T>&);
@@ -510,9 +511,19 @@ public:
 
     // Special Methods
 
-        //- A bitSet::test() method for a list of bool
-        //
-        //  \return The element value, or false for out-of-range access
+        //- Test \c bool value at specified position,
+        //- always false for out-of-range access. Same as test().
+        //  \note Predicate definition as per bitSet, HashSet
+        template<class TypeT = T>
+        typename std::enable_if<std::is_same<bool, TypeT>::value, bool>::type
+        inline operator()(const label i) const
+        {
+            return (i >= 0 && i < size_ && v_[i]);
+        }
+
+        //- Test \c bool value at specified position,
+        //- always false for out-of-range access.
+        //  \note Method name compatibility with bitSet, HashSet
         template<class TypeT = T>
         typename std::enable_if<std::is_same<bool, TypeT>::value, bool>::type
         inline test(const label i) const
@@ -520,9 +531,9 @@ public:
             return (i >= 0 && i < size_ && v_[i]);
         }
 
-        //- A bitSet::get() method for a list of bool
-        //
-        //  \return The element value, or false for out-of-range access
+        //- Return \c bool value at specified position,
+        //- always false for out-of-range access.
+        //  \note Method name compatibility with bitSet
         template<class TypeT = T>
         typename std::enable_if<std::is_same<bool, TypeT>::value, bool>::type
         inline get(const label i) const
@@ -530,9 +541,10 @@ public:
             return (i >= 0 && i < size_ && v_[i]);
         }
 
-        //- A bitSet::unset() method for a list of bool
-        //
+        //- Unset the \c bool entry at specified position,
+        //- always false for out-of-range access.
         //  \return True if value changed and was not out-of-range
+        //  \note Method name compatibility with bitSet
         template<class TypeT = T>
         typename std::enable_if<std::is_same<bool, TypeT>::value, bool>::type
         inline unset(const label i)
@@ -624,26 +636,31 @@ Ostream& operator<<(Ostream& os, const std::vector<T>& list);
 
 // * * * * * * * * * * * * * * Global Functions  * * * * * * * * * * * * * * //
 
+//- Sort the list
 template<class T>
-void sort(UList<T>& a);
+void sort(UList<T>& list);
 
+//- Sort the list with the specified comparator
 template<class T, class Compare>
-void sort(UList<T>& a, const Compare& comp);
+void sort(UList<T>& list, const Compare& comp);
 
+//- Stable sort the list
 template<class T>
-void stableSort(UList<T>& a);
+void stableSort(UList<T>& list);
 
+//- Stable sort the list with the specified comparator
 template<class T, class Compare>
-void stableSort(UList<T>& a, const Compare& comp);
+void stableSort(UList<T>& list, const Compare& comp);
 
+//- Randomise the list order
 template<class T>
-void shuffle(UList<T>& a);
+void shuffle(UList<T>& list);
 
-// Reverse the first n elements of the list
+//- Reverse the first n elements of the list
 template<class T>
 inline void reverse(UList<T>& list, const label n);
 
-// Reverse all the elements of the list
+//- Reverse all elements of the list
 template<class T>
 inline void reverse(UList<T>& list);
 
diff --git a/src/OpenFOAM/containers/Lists/UList/UListI.H b/src/OpenFOAM/containers/Lists/List/UListI.H
similarity index 98%
rename from src/OpenFOAM/containers/Lists/UList/UListI.H
rename to src/OpenFOAM/containers/Lists/List/UListI.H
index 391f264464..013a617a8b 100644
--- a/src/OpenFOAM/containers/Lists/UList/UListI.H
+++ b/src/OpenFOAM/containers/Lists/List/UListI.H
@@ -448,7 +448,9 @@ inline void Foam::UList<T>::swap(UList<T>& list)
 template<class T>
 inline void Foam::reverse(UList<T>& list, const label n)
 {
-    for (label i=0; i<n/2; ++i)
+    const label nBy2 = n/2;
+
+    for (label i = 0; i < nBy2; ++i)
     {
         Foam::Swap(list[i], list[n-1-i]);
     }
@@ -458,7 +460,7 @@ inline void Foam::reverse(UList<T>& list, const label n)
 template<class T>
 inline void Foam::reverse(UList<T>& list)
 {
-    reverse(list, list.size());
+    Foam::reverse(list, list.size());
 }
 
 
diff --git a/src/OpenFOAM/containers/Lists/UList/UListIO.C b/src/OpenFOAM/containers/Lists/List/UListIO.C
similarity index 100%
rename from src/OpenFOAM/containers/Lists/UList/UListIO.C
rename to src/OpenFOAM/containers/Lists/List/UListIO.C
diff --git a/src/OpenFOAM/containers/Lists/UList/stdVectorIO.C b/src/OpenFOAM/containers/Lists/List/stdVectorIO.C
similarity index 100%
rename from src/OpenFOAM/containers/Lists/UList/stdVectorIO.C
rename to src/OpenFOAM/containers/Lists/List/stdVectorIO.C
diff --git a/src/OpenFOAM/containers/Lists/ListOps/ListOps.H b/src/OpenFOAM/containers/Lists/ListOps/ListOps.H
index 81dfaad569..1ac082a857 100644
--- a/src/OpenFOAM/containers/Lists/ListOps/ListOps.H
+++ b/src/OpenFOAM/containers/Lists/ListOps/ListOps.H
@@ -48,6 +48,7 @@ SourceFiles
 #include "FlatOutput.H"
 #include "labelPair.H"
 #include "labelList.H"
+#include "IndirectList.H"
 #include "HashSet.H"
 #include "Map.H"
 #include "bitSet.H"
@@ -178,24 +179,6 @@ template<class Container>
 label inplaceMapValue(const Map<label>& mapper, Container& input);
 
 
-//- Return the (stable) sort order for the list
-template<class T>
-labelList sortedOrder(const UList<T>& input);
-
-//- Generate the (stable) sort order for the list
-template<class T>
-void sortedOrder(const UList<T>& input, labelList& order);
-
-//- Sort using specified list compare predicate
-template<class T, class ListComparePredicate>
-void sortedOrder
-(
-    const UList<T>& input,
-    labelList& order,
-    const ListComparePredicate& comp
-);
-
-
 //- Return (sorted) indices corresponding to duplicate list values
 template<class T>
 labelList duplicateOrder(const UList<T>& input);
@@ -263,6 +246,7 @@ void inplaceUniqueSort
 //  \endcode
 //
 //  \return The subsetted list
+//  \see IndirectList::subset
 template<class BoolListType, class T>
 List<T> subset
 (
@@ -278,6 +262,7 @@ List<T> subset
 //  \param[in] invert set as true to invert the selection logic
 //
 //  \return The subsetted list
+//  \see IndirectList::subset
 template<class T>
 List<T> subset
 (
@@ -320,9 +305,12 @@ void inplaceSubset
 
 //- Copy a subset of the input list when predicate is true.
 //
-//  \param[in,out] input the list input values.
+//  \param[in] input the list input values.
 //  \param[in] pred the selection predicate
 //  \param[in] invert set as true to invert the selection logic
+//
+//  \return The subsetted list
+//  \see IndirectList::subset_if
 template<class T, class UnaryPredicate>
 List<T> subsetList
 (
diff --git a/src/OpenFOAM/containers/Lists/ListOps/ListOpsTemplates.C b/src/OpenFOAM/containers/Lists/ListOps/ListOpsTemplates.C
index 24846e7875..0b4885f957 100644
--- a/src/OpenFOAM/containers/Lists/ListOps/ListOpsTemplates.C
+++ b/src/OpenFOAM/containers/Lists/ListOps/ListOpsTemplates.C
@@ -321,46 +321,6 @@ Foam::label Foam::inplaceMapValue
 }
 
 
-template<class T>
-Foam::labelList Foam::sortedOrder
-(
-    const UList<T>& input
-)
-{
-    labelList order;
-    sortedOrder(input, order, typename UList<T>::less(input));
-    return order;
-}
-
-
-template<class T>
-void Foam::sortedOrder
-(
-    const UList<T>& input,
-    labelList& order
-)
-{
-    sortedOrder(input, order, typename UList<T>::less(input));
-}
-
-
-template<class T, class ListComparePredicate>
-void Foam::sortedOrder
-(
-    const UList<T>& input,
-    labelList& order,
-    const ListComparePredicate& comp
-)
-{
-    // List lengths must be identical. Old content is overwritten
-    order.resize_nocopy(input.size());
-
-    ListOps::identity(order);
-
-    Foam::stableSort(order, comp);
-}
-
-
 template<class T>
 Foam::labelList Foam::duplicateOrder
 (
@@ -398,7 +358,7 @@ void Foam::duplicateOrder
         return;
     }
 
-    sortedOrder(input, order, comp);
+    Foam::sortedOrder(input, order, comp);
 
     const label last = (order.size()-1);
     label count = 0;
@@ -445,7 +405,7 @@ void Foam::uniqueOrder
     const ListComparePredicate& comp
 )
 {
-    sortedOrder(input, order, comp);
+    Foam::sortedOrder(input, order, comp);
 
     if (order.size() > 1)
     {
diff --git a/src/OpenFOAM/containers/Lists/SortableList/SortableList.C b/src/OpenFOAM/containers/Lists/SortableList/SortableList.C
index 28288a5bc0..ed2aa47fab 100644
--- a/src/OpenFOAM/containers/Lists/SortableList/SortableList.C
+++ b/src/OpenFOAM/containers/Lists/SortableList/SortableList.C
@@ -26,7 +26,7 @@ License
 
 \*---------------------------------------------------------------------------*/
 
-#include "ListOps.H"
+#include "ListOps.H"  // For identity
 
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
diff --git a/src/OpenFOAM/containers/PtrLists/PtrListDetail/PtrListDetail.C b/src/OpenFOAM/containers/PtrLists/PtrListDetail/PtrListDetail.C
index a72ec9461a..a71e0f4a19 100644
--- a/src/OpenFOAM/containers/PtrLists/PtrListDetail/PtrListDetail.C
+++ b/src/OpenFOAM/containers/PtrLists/PtrListDetail/PtrListDetail.C
@@ -50,6 +50,9 @@ Foam::label Foam::Detail::PtrListDetail<T>::count() const
 template<class T>
 Foam::label Foam::Detail::PtrListDetail<T>::findNull() const
 {
+    // Same as  List<T*>::find(nullptr);
+    // except perhaps without pointer ambiguities...
+
     label idx = 0;
 
     for (const T* ptr : *this)
diff --git a/src/OpenFOAM/containers/PtrLists/PtrListDetail/PtrListDetail.H b/src/OpenFOAM/containers/PtrLists/PtrListDetail/PtrListDetail.H
index 8e7ccf4372..70b4637c3b 100644
--- a/src/OpenFOAM/containers/PtrLists/PtrListDetail/PtrListDetail.H
+++ b/src/OpenFOAM/containers/PtrLists/PtrListDetail/PtrListDetail.H
@@ -42,8 +42,8 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef PtrListDetail_H
-#define PtrListDetail_H
+#ifndef Foam_PtrListDetail_H
+#define Foam_PtrListDetail_H
 
 #include "List.H"
 
@@ -92,9 +92,12 @@ public:
         //- Return the count of non-nullptr entries
         label count() const;
 
-        //- Locate the first null entry, -1 if there are not any
+        //- Locate the first null entry, -1 if there are none (or empty list)
         label findNull() const;
 
+        //- FatalError if any null exists in the list
+        inline void checkNonNull() const;
+
         //- Assign all pointers to nullptr, without deleting.
         void setNull();
 
diff --git a/src/OpenFOAM/containers/PtrLists/PtrListDetail/PtrListDetailI.H b/src/OpenFOAM/containers/PtrLists/PtrListDetail/PtrListDetailI.H
index a8777f39ad..7b5425c1f4 100644
--- a/src/OpenFOAM/containers/PtrLists/PtrListDetail/PtrListDetailI.H
+++ b/src/OpenFOAM/containers/PtrLists/PtrListDetail/PtrListDetailI.H
@@ -109,6 +109,20 @@ inline void Foam::Detail::PtrListDetail<T>::resize(const label newLen)
 }
 
 
+template<class T>
+inline void Foam::Detail::PtrListDetail<T>::checkNonNull() const
+{
+    const label idx = this->findNull();
+
+    if (idx >= 0)
+    {
+        FatalErrorInFunction
+            << "Element " << idx << " is null" << nl
+            << abort(FatalError);
+    }
+}
+
+
 // * * * * * * * * * * * * * * * Member Operators  * * * * * * * * * * * * * //
 
 template<class T>
diff --git a/src/OpenFOAM/containers/PtrLists/PtrListOps/PtrListOps.H b/src/OpenFOAM/containers/PtrLists/PtrListOps/PtrListOps.H
index 8bd574602d..bdc9df5f71 100644
--- a/src/OpenFOAM/containers/PtrLists/PtrListOps/PtrListOps.H
+++ b/src/OpenFOAM/containers/PtrLists/PtrListOps/PtrListOps.H
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019-2021 OpenCFD Ltd.
+    Copyright (C) 2019-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -40,8 +40,8 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef PtrListOps_H
-#define PtrListOps_H
+#ifndef Foam_PtrListOps_H
+#define Foam_PtrListOps_H
 
 #include "predicates.H"
 #include "PtrList.H"
@@ -54,31 +54,23 @@ namespace Foam
 
 //- Return (stable) sort order for the list
 template<class T>
-labelList sortedOrder(const UPtrList<T>& input);
+labelList sortedOrder(const UPtrList<T>& list);
 
 //- Generate (stable) sort order for the list
 template<class T>
-void sortedOrder(const UPtrList<T>& input, labelList& order);
+void sortedOrder(const UPtrList<T>& list, labelList& order);
 
 //- Generate (stable) sort order for the list,
 //- using the specified list compare predicate
 template<class T, class ListComparePredicate>
 void sortedOrder
 (
-    const UPtrList<T>& input,
+    const UPtrList<T>& list,
     labelList& order,
     const ListComparePredicate& comp
 );
 
 
-//- Inplace (stable) sorting of pointer list.
-template<class T>
-void sort(UPtrList<T>& list);
-
-//- Inplace (stable) sorting of pointer list.
-template<class T, class Compare>
-void sort(UPtrList<T>& list, const Compare& comp);
-
 //- Inplace shuffle of pointer list.
 template<class T>
 void shuffle(UPtrList<T>& list);
@@ -91,52 +83,6 @@ void shuffle(UPtrList<T>& list);
 namespace PtrListOps
 {
 
-// Public Classes
-
-//- A UPtrList compare binary predicate for normal sort.
-//  Null entries sort to the end
-template<class T>
-struct less
-{
-    const UPtrList<T>& values;
-
-    less(const UPtrList<T>& list)
-    :
-        values(list)
-    {}
-
-    bool operator()(const label a, const label b) const
-    {
-        const T* const ptr1 = values(a);
-        const T* const ptr2 = values(b);
-
-        return (ptr1 && ptr2) ? (*ptr1 < *ptr2) : !ptr2;
-    }
-};
-
-
-//- A UPtrList compare binary predicate for reverse sort.
-//  Null entries sort to the end
-template<class T>
-struct greater
-{
-    const UPtrList<T>& values;
-
-    greater(const UPtrList<T>& list)
-    :
-        values(list)
-    {}
-
-    bool operator()(const label a, const label b) const
-    {
-        const T* const ptr1 = values(a);
-        const T* const ptr2 = values(b);
-
-        return (ptr1 && ptr2) ? (*ptr2 < *ptr1) : !ptr2;
-    }
-};
-
-
 //- List of values generated by applying the access operation
 //- to each list item.
 //
diff --git a/src/OpenFOAM/containers/PtrLists/PtrListOps/PtrListOpsTemplates.C b/src/OpenFOAM/containers/PtrLists/PtrListOps/PtrListOpsTemplates.C
index aec159d25f..85d6fedf70 100644
--- a/src/OpenFOAM/containers/PtrLists/PtrListOps/PtrListOpsTemplates.C
+++ b/src/OpenFOAM/containers/PtrLists/PtrListOps/PtrListOpsTemplates.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019-2021 OpenCFD Ltd.
+    Copyright (C) 2019-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -32,11 +32,11 @@ License
 template<class T>
 Foam::labelList Foam::sortedOrder
 (
-    const UPtrList<T>& input
+    const UPtrList<T>& list
 )
 {
     labelList order;
-    sortedOrder(input, order, typename PtrListOps::less<T>(input));
+    Foam::sortedOrder(list, order, typename UPtrList<T>::less(list));
     return order;
 }
 
@@ -44,59 +44,49 @@ Foam::labelList Foam::sortedOrder
 template<class T>
 void Foam::sortedOrder
 (
-    const UPtrList<T>& input,
+    const UPtrList<T>& list,
     labelList& order
 )
 {
-    sortedOrder(input, order, typename PtrListOps::less<T>(input));
+    Foam::sortedOrder(list, order, typename UPtrList<T>::less(list));
 }
 
 
 template<class T, class ListComparePredicate>
 void Foam::sortedOrder
 (
-    const UPtrList<T>& input,
+    const UPtrList<T>& list,
     labelList& order,
     const ListComparePredicate& comp
 )
 {
     // List lengths must be identical. Old content is overwritten
-    order.resize_nocopy(input.size());
+    order.resize_nocopy(list.size());
 
-    ListOps::identity(order);
+    // Same as std::iota and ListOps::identity
+    label value = 0;
+    for (label& item : order)
+    {
+        item = value;
+        ++value;
+    }
 
-    Foam::stableSort(order, comp);
-}
-
-
-template<class T>
-void Foam::sort(UPtrList<T>& list)
-{
-    labelList order;
-    sortedOrder(list, order);
-    list.sortOrder(order, false);  // false = allow nullptr
-}
-
-
-template<class T, class Compare>
-void Foam::sort(UPtrList<T>& list, const Compare& comp)
-{
-    labelList order;
-    sortedOrder(list, order, comp);
-    list.sortOrder(order, false);  // false = allow nullptr
+    std::stable_sort(order.begin(), order.end(), comp);
 }
 
 
 template<class T>
 void Foam::shuffle(UPtrList<T>& list)
 {
+    // Cannot use std::shuffle directly since that would dereference
+    // the list entries, which may contain null pointers.
+    // The alternative would be to expose the pointer details (a bit ugly).
     labelList order(identity(list.size()));
     Foam::shuffle(order);
-    list.sortOrder(order, false);  // false = allow nullptr
+    list.sortOrder(order, false);  // false = no nullptr check
 }
 
 
-
 // Templated implementation for types(), names(), etc - file-scope
 template<class ReturnType, class T, class AccessOp>
 Foam::List<ReturnType> Foam::PtrListOps::get
diff --git a/src/OpenFOAM/containers/PtrLists/UPtrList/UPtrList.C b/src/OpenFOAM/containers/PtrLists/UPtrList/UPtrList.C
index 476054ef50..9ae4fcdec7 100644
--- a/src/OpenFOAM/containers/PtrLists/UPtrList/UPtrList.C
+++ b/src/OpenFOAM/containers/PtrLists/UPtrList/UPtrList.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2015-2019 OpenCFD Ltd.
+    Copyright (C) 2015-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -66,11 +66,7 @@ Foam::label Foam::UPtrList<T>::squeezeNull()
 
 
 template<class T>
-void Foam::UPtrList<T>::reorder
-(
-    const labelUList& oldToNew,
-    const bool testNull
-)
+void Foam::UPtrList<T>::reorder(const labelUList& oldToNew, const bool check)
 {
     const label len = this->size();
 
@@ -87,37 +83,31 @@ void Foam::UPtrList<T>::reorder
 
     for (label i=0; i<len; ++i)
     {
-        const label idx = oldToNew[i];
+        const label newIdx = oldToNew[i];
 
-        if (idx < 0 || idx >= len)
+        if (newIdx < 0 || newIdx >= len)
         {
             FatalErrorInFunction
-                << "Illegal index " << idx << nl
+                << "Illegal index " << newIdx << nl
                 << "Valid indices are [0," << len << ") for type "
                 << typeid(T).name() << nl
                 << abort(FatalError);
         }
 
-        if (newList[idx])
+        if (newList[newIdx])
         {
             FatalErrorInFunction
-                << "reorder map is not unique; element " << idx
+                << "reorder map is not unique; element " << newIdx
                 << " already used for type " << typeid(T).name()
                 << abort(FatalError);
         }
-        newList[idx] = ptrs_[i];
+        newList[newIdx] = ptrs_[i];
     }
 
-    // Verify that all pointers were indeed set
-    if (testNull)
+    // Verify all pointers were indeed set
+    if (check)
     {
-        const label idx = newList.findNull();
-        if (idx >= 0)
-        {
-            FatalErrorInFunction
-                << "Element " << idx << " not set after reordering." << nl
-                << abort(FatalError);
-        }
+        newList.checkNonNull();
     }
 
     ptrs_.transfer(newList);
@@ -125,11 +115,7 @@ void Foam::UPtrList<T>::reorder
 
 
 template<class T>
-void Foam::UPtrList<T>::sortOrder
-(
-    const labelUList& order,
-    const bool testNull
-)
+void Foam::UPtrList<T>::sortOrder(const labelUList& order, const bool check)
 {
     const label len = this->size();
 
@@ -147,39 +133,33 @@ void Foam::UPtrList<T>::sortOrder
 
     for (label i=0; i<len; ++i)
     {
-        const label idx = order[i];
+        const label oldIdx = order[i];
 
-        if (idx < 0 || idx >= len)
+        if (oldIdx < 0 || oldIdx >= len)
         {
             FatalErrorInFunction
-                << "Illegal index " << idx << nl
+                << "Illegal index " << oldIdx << nl
                 << "Valid indices are [0," << len << ") for type "
                 << typeid(T).name() << nl
                 << abort(FatalError);
         }
 
-        if (guard[idx])
+        if (guard[oldIdx])
         {
             FatalErrorInFunction
-                << "order map is not unique; element " << idx
+                << "order map is not unique; element " << oldIdx
                 << " already used for type " << typeid(T).name()
                 << abort(FatalError);
         }
 
-        guard[idx] = ptrs_[idx];
-        newList[i] = ptrs_[idx];
+        guard[oldIdx] = ptrs_[oldIdx];
+        newList[i] = ptrs_[oldIdx];
     }
 
     // Verify that all pointers were indeed set
-    if (testNull)
+    if (check)
     {
-        const label idx = newList.findNull();
-        if (idx >= 0)
-        {
-            FatalErrorInFunction
-                << "Element " << idx << " not set after reordering." << nl
-                << abort(FatalError);
-        }
+        newList.checkNonNull();
     }
 
     ptrs_.transfer(newList);
@@ -195,4 +175,26 @@ Foam::Ostream& Foam::operator<<(Ostream& os, const UPtrList<T>& list)
 }
 
 
+// * * * * * * * * * * * * * * * Global Functions  * * * * * * * * * * * * * //
+
+template<class T, class Compare>
+void Foam::sort(UPtrList<T>& list, const Compare& comp)
+{
+    std::stable_sort
+    (
+        list.begin_ptr(),
+        list.end_ptr(),
+        typename UPtrList<T>::template value_compare<Compare>(comp)
+    );
+}
+
+
+template<class T>
+void Foam::sort(UPtrList<T>& list)
+{
+    // ie, lessOp<T>() or std::less<T>()
+    Foam::sort(list, [](const T& a, const T& b) { return (a < b); });
+}
+
+
 // ************************************************************************* //
diff --git a/src/OpenFOAM/containers/PtrLists/UPtrList/UPtrList.H b/src/OpenFOAM/containers/PtrLists/UPtrList/UPtrList.H
index 0cf8642626..4f88822e98 100644
--- a/src/OpenFOAM/containers/PtrLists/UPtrList/UPtrList.H
+++ b/src/OpenFOAM/containers/PtrLists/UPtrList/UPtrList.H
@@ -110,6 +110,72 @@ public:
         class const_iterator;
 
 
+    // Public Classes
+
+        //- A wrapper for a binary comparison of values that interjects
+        //- pointer dereferencing with null pointer guards.
+        //  It will also sort any null pointers to the end
+        //  (eg, rubbish that can be truncated)
+        template<class Compare>
+        struct value_compare
+        {
+            const Compare& comp;
+
+            value_compare(const Compare& cmp)
+            :
+                comp(cmp)
+            {}
+
+            //- Compare dereferenced pointers
+            bool operator()(const T* const a, const T* const b) const
+            {
+                return (a && b) ? comp(*a, *b) : bool(a);
+            }
+        };
+
+        //- A UPtrList compare binary predicate for normal sort order.
+        //- Null entries (if any) sort to the end.
+        struct less
+        {
+            const UPtrList<T>& values;
+
+            less(const UPtrList<T>& list)
+            :
+                values(list)
+            {}
+
+            //- Compare dereferenced pointer locations for normal sort.
+            bool operator()(const label ai, const label bi) const
+            {
+                const T* const a = values.get(ai);
+                const T* const b = values.get(bi);
+
+                return (a && b) ? (*a < *b) : bool(a);
+            }
+        };
+
+        //- A UPtrList compare binary predicate for reverse sort order.
+        //  Null entries (if any) sort to the end.
+        struct greater
+        {
+            const UPtrList<T>& values;
+
+            greater(const UPtrList<T>& list)
+            :
+                values(list)
+            {}
+
+            //- Compare dereferenced pointer locations for reverse sort
+            bool operator()(const label ai, const label bi) const
+            {
+                const T* const a = values.get(ai);
+                const T* const b = values.get(bi);
+
+                return (a && b) ? (*b < *a) : bool(b);
+            }
+        };
+
+
     // Constructors
 
         //- Default construct
@@ -215,13 +281,19 @@ public:
 
         //- Reorder elements.
         //- Reordering must be unique (ie, shuffle).
-        //  Optionally verify that all pointers have been set.
-        void reorder(const labelUList& oldToNew, const bool testNull = true);
+        //  Optionally check that all pointers have been set.
+        void reorder(const labelUList& oldToNew, const bool check = false);
 
         //- Reorder elements according to new order mapping (newToOld).
         //- Reordering must be unique (ie, shuffle).
-        //  Optionally verify that all pointers have been set.
-        void sortOrder(const labelUList& order, const bool testNull = true);
+        //  Optionally check that all pointers have been set.
+        void sortOrder(const labelUList& order, const bool check = false);
+
+
+    // Checks
+
+        //- Check and raise FatalError if any nullptr exists in the list
+        inline void checkNonNull() const;
 
 
     // Member Operators
@@ -362,22 +434,29 @@ public:
         };
 
 
-        //- Return an iterator to begin traversing the UPtrList
+        //- Iterator to begin of raw pointers traversal (use with caution)
+        T** begin_ptr() noexcept { return ptrs_.begin(); }
+
+        //- Iterator beyond end of raw pointers traversal (use with caution)
+        T** end_ptr() noexcept { return ptrs_.end(); }
+
+
+        //- Return an iterator to begin of UPtrList traversal
         inline iterator begin() noexcept;
 
-        //- Return an iterator to end traversing the UPtrList
+        //- Return iterator beyond end of UPtrList traversal
         inline iterator end() noexcept;
 
-        //- Return an const_iterator to begin traversing the UPtrList
+        //- Return const_iterator to begin of UPtrList traversal
         inline const_iterator cbegin() const noexcept;
 
-        //- Return an const_iterator to end traversing the UPtrList
+        //- Return const_iterator beyond end of UPtrList traversal
         inline const_iterator cend() const noexcept;
 
-        //- Return an const_iterator to begin traversing the UPtrList
+        //- Return const_iterator to begin of UPtrList traversal
         inline const_iterator begin() const noexcept;
 
-        //- Return an const_iterator to end traversing the UPtrList
+        //- Return const_iterator beyond end of UPtrList traversal
         inline const_iterator end() const noexcept;
 
 
@@ -392,6 +471,20 @@ public:
 };
 
 
+// * * * * * * * * * * * * * * Global Functions  * * * * * * * * * * * * * * //
+
+//- Inplace (stable) sorting of pointer list.
+template<class T>
+void sort(UPtrList<T>& list);
+
+//- Inplace (stable) sorting of pointer list using given comparator,
+//- which compares objects, not pointers.
+//  This sort function includes null pointer guards and will also sort
+//  any null pointers to the end (eg, rubbish that can be truncated)
+template<class T, class Compare>
+void sort(UPtrList<T>& list, const Compare& comp);
+
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 } // End namespace Foam
diff --git a/src/OpenFOAM/containers/PtrLists/UPtrList/UPtrListI.H b/src/OpenFOAM/containers/PtrLists/UPtrList/UPtrListI.H
index 0bc1262089..1716ddf253 100644
--- a/src/OpenFOAM/containers/PtrLists/UPtrList/UPtrListI.H
+++ b/src/OpenFOAM/containers/PtrLists/UPtrList/UPtrListI.H
@@ -215,6 +215,13 @@ inline T* Foam::UPtrList<T>::set(const label i, T* ptr)
 }
 
 
+template<class T>
+inline void Foam::UPtrList<T>::checkNonNull() const
+{
+    ptrs_.checkNonNull();
+}
+
+
 // * * * * * * * * * * * * * * * Member Operators  * * * * * * * * * * * * * //
 
 template<class T>
diff --git a/src/OpenFOAM/db/IOobjects/IOField/IOField.C b/src/OpenFOAM/db/IOobjects/IOField/IOField.C
index af07c9e91a..bb84a52e0c 100644
--- a/src/OpenFOAM/db/IOobjects/IOField/IOField.C
+++ b/src/OpenFOAM/db/IOobjects/IOField/IOField.C
@@ -167,12 +167,33 @@ Foam::IOField<Type>::IOField(const IOobject& io, const tmp<Field<Type>>& tfld)
 }
 
 
+template<class Type>
+Foam::IOFieldRef<Type>::IOFieldRef
+(
+    const IOobject& io,
+    const Field<Type>& content
+)
+:
+    regIOobject(io),
+    contentRef_(content)  // cref
+{}
+
+
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
 template<class Type>
 bool Foam::IOField<Type>::writeData(Ostream& os) const
 {
-    return (os << static_cast<const Field<Type>&>(*this)).good();
+    os << static_cast<const Field<Type>&>(*this);
+    return os.good();
+}
+
+
+template<class Type>
+bool Foam::IOFieldRef<Type>::writeData(Ostream& os) const
+{
+    os << contentRef_.cref();
+    return os.good();
 }
 
 
diff --git a/src/OpenFOAM/db/IOobjects/IOField/IOField.H b/src/OpenFOAM/db/IOobjects/IOField/IOField.H
index 163ee129df..7dc71fdf14 100644
--- a/src/OpenFOAM/db/IOobjects/IOField/IOField.H
+++ b/src/OpenFOAM/db/IOobjects/IOField/IOField.H
@@ -38,8 +38,9 @@ SourceFiles
 #ifndef Foam_IOField_H
 #define Foam_IOField_H
 
-#include "regIOobject.H"
 #include "Field.H"
+#include "regIOobject.H"
+#include "refPtr.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
@@ -100,7 +101,8 @@ public:
 
     // Member Functions
 
-        bool writeData(Ostream& os) const;
+        //- The writeData method for regIOobject write operation
+        virtual bool writeData(Ostream& os) const;
 
 
     // Member Operators
@@ -113,6 +115,72 @@ public:
 };
 
 
+/*---------------------------------------------------------------------------*\
+                         Class IOFieldRef Declaration
+\*---------------------------------------------------------------------------*/
+
+//- A IOField wrapper for writing external data.
+template<class Type>
+class IOFieldRef
+:
+    public regIOobject
+{
+    // Private Data
+
+        //- Reference to the external content
+        refPtr<Field<Type>> contentRef_;
+
+
+public:
+
+    //- The underlying content type
+    typedef Field<Type> content_type;
+
+
+    //- Type is identical to IOField
+    virtual const word& type() const
+    {
+        return IOField<Type>::typeName;
+    }
+
+
+    // Generated Methods
+
+        //- No default construct
+        IOFieldRef() = delete;
+
+        //- No copy construct
+        IOFieldRef(const IOFieldRef&) = delete;
+
+        //- No copy assignment
+        void operator=(const IOFieldRef&) = delete;
+
+
+    // Constructors
+
+        //- Construct from IOobject and const data reference
+        IOFieldRef(const IOobject& io, const Field<Type>& content);
+
+
+    //- Destructor
+    virtual ~IOFieldRef() = default;
+
+
+    // Member Functions
+
+        //- Allow cast to const content
+        //  Fatal if content is not set
+        operator const Field<Type>&() const
+        {
+            return contentRef_.cref();
+        }
+
+        //- The writeData method for regIOobject write operation
+        //  Fatal if content is not set
+        virtual bool writeData(Ostream& os) const;
+};
+
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 } // End namespace Foam
diff --git a/src/OpenFOAM/db/IOobjects/IOList/IOList.C b/src/OpenFOAM/db/IOobjects/IOList/IOList.C
index 9c96b75374..a058b52442 100644
--- a/src/OpenFOAM/db/IOobjects/IOList/IOList.C
+++ b/src/OpenFOAM/db/IOobjects/IOList/IOList.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2016-2018 OpenCFD Ltd.
+    Copyright (C) 2016-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -109,12 +109,33 @@ Foam::IOList<T>::IOList(const IOobject& io, List<T>&& content)
 }
 
 
+template<class T>
+Foam::IOListRef<T>::IOListRef
+(
+    const IOobject& io,
+    const List<T>& content
+)
+:
+    regIOobject(io),
+    contentRef_(content)
+{}
+
+
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
 template<class T>
 bool Foam::IOList<T>::writeData(Ostream& os) const
 {
-    return (os << *this).good();
+    os << static_cast<const List<T>&>(*this);
+    return os.good();
+}
+
+
+template<class T>
+bool Foam::IOListRef<T>::writeData(Ostream& os) const
+{
+    os << contentRef_.cref();
+    return os.good();
 }
 
 
diff --git a/src/OpenFOAM/db/IOobjects/IOList/IOList.H b/src/OpenFOAM/db/IOobjects/IOList/IOList.H
index 86cd0a1eb7..3894f96a3d 100644
--- a/src/OpenFOAM/db/IOobjects/IOList/IOList.H
+++ b/src/OpenFOAM/db/IOobjects/IOList/IOList.H
@@ -40,6 +40,7 @@ SourceFiles
 
 #include "List.H"
 #include "regIOobject.H"
+#include "refPtr.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
@@ -94,7 +95,8 @@ public:
 
     // Member Functions
 
-        bool writeData(Ostream& os) const;
+        //- The writeData method for regIOobject write operation
+        virtual bool writeData(Ostream& os) const;
 
 
     // Member Operators
@@ -107,6 +109,72 @@ public:
 };
 
 
+/*---------------------------------------------------------------------------*\
+                          Class IOListRef Declaration
+\*---------------------------------------------------------------------------*/
+
+//- A IOList wrapper for writing external data.
+template<class T>
+class IOListRef
+:
+    public regIOobject
+{
+    // Private Data
+
+        //- Reference to the external content
+        refPtr<List<T>> contentRef_;
+
+
+public:
+
+    //- The underlying content type
+    typedef List<T> content_type;
+
+
+    //- Type is identical to IOList
+    virtual const word& type() const
+    {
+        return IOList<T>::typeName;
+    }
+
+
+    // Generated Methods
+
+        //- No default construct
+        IOListRef() = delete;
+
+        //- No copy construct
+        IOListRef(const IOListRef&) = delete;
+
+        //- No copy assignment
+        void operator=(const IOListRef&) = delete;
+
+
+    // Constructors
+
+        //- Construct from IOobject and const data reference
+        IOListRef(const IOobject& io, const List<T>& content);
+
+
+    //- Destructor
+    virtual ~IOListRef() = default;
+
+
+    // Member Functions
+
+        //- Allow cast to const content
+        //  Fatal if content is not set
+        operator const List<T>&() const
+        {
+            return contentRef_.cref();
+        }
+
+        //- The writeData method for regIOobject write operation
+        //  Fatal if content is not set
+        virtual bool writeData(Ostream& os) const;
+};
+
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 } // End namespace Foam
diff --git a/src/OpenFOAM/db/IOobjects/IOMap/IOMap.C b/src/OpenFOAM/db/IOobjects/IOMap/IOMap.C
index fc1bdd57dc..b44711ee55 100644
--- a/src/OpenFOAM/db/IOobjects/IOMap/IOMap.C
+++ b/src/OpenFOAM/db/IOobjects/IOMap/IOMap.C
@@ -106,7 +106,8 @@ Foam::IOMap<T>::IOMap(const IOobject& io, Map<T>&& content)
 template<class T>
 bool Foam::IOMap<T>::writeData(Ostream& os) const
 {
-    return (os << *this).good();
+    os << *this;
+    return os.good();
 }
 
 
diff --git a/src/OpenFOAM/db/IOobjects/IOMap/IOMapName.C b/src/OpenFOAM/db/IOobjects/IOMap/IOMaps.C
similarity index 100%
rename from src/OpenFOAM/db/IOobjects/IOMap/IOMapName.C
rename to src/OpenFOAM/db/IOobjects/IOMap/IOMaps.C
diff --git a/src/OpenFOAM/matrices/lduMatrix/lduAddressing/lduSchedule/lduSchedule.H b/src/OpenFOAM/matrices/lduMatrix/lduAddressing/lduSchedule/lduSchedule.H
index 945b1bde37..8af52779e3 100644
--- a/src/OpenFOAM/matrices/lduMatrix/lduAddressing/lduSchedule/lduSchedule.H
+++ b/src/OpenFOAM/matrices/lduMatrix/lduAddressing/lduSchedule/lduSchedule.H
@@ -32,8 +32,8 @@ Description
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef lduSchedule_H
-#define lduSchedule_H
+#ifndef Foam_lduSchedule_H
+#define Foam_lduSchedule_H
 
 #include "List.H"
 
@@ -42,14 +42,17 @@ Description
 namespace Foam
 {
 
-// Forward declaration of friend functions and operators
+// Forward Declarations
 
 struct lduScheduleEntry;
 Ostream& operator<<(Ostream& os, const lduScheduleEntry& lb);
 
+//- A List of lduSchedule entries.
+typedef List<lduScheduleEntry> lduSchedule;
+
 
 /*---------------------------------------------------------------------------*\
-                      Class lduSchedule Declaration
+                      Class lduScheduleEntry Declaration
 \*---------------------------------------------------------------------------*/
 
 struct lduScheduleEntry
@@ -57,11 +60,22 @@ struct lduScheduleEntry
     label patch;
     bool init;
 
-    friend bool operator!=
-    (
-        const lduScheduleEntry& lb1,
-        const lduScheduleEntry& lb2
-    )
+    //- Define patch for initEvaluate()
+    void setInitEvaluate(const label patchi) noexcept
+    {
+        patch = patchi;
+        init = true;
+    }
+
+    //- Define patch for evaluate()
+    void setEvaluate(const label patchi) noexcept
+    {
+        patch = patchi;
+        init = false;
+    }
+
+    //- Always unequal: each entry is supposed to be unique!
+    friend bool operator!=(const lduScheduleEntry&, const lduScheduleEntry&)
     {
         return true;
     }
@@ -74,9 +88,6 @@ struct lduScheduleEntry
 };
 
 
-typedef List<lduScheduleEntry> lduSchedule;
-
-
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 } // End namespace Foam
diff --git a/src/OpenFOAM/meshes/ProcessorTopology/ProcessorTopology.C b/src/OpenFOAM/meshes/ProcessorTopology/ProcessorTopology.C
deleted file mode 100644
index 359f7ae0b9..0000000000
--- a/src/OpenFOAM/meshes/ProcessorTopology/ProcessorTopology.C
+++ /dev/null
@@ -1,273 +0,0 @@
-/*---------------------------------------------------------------------------*\
-  =========                 |
-  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
-   \\    /   O peration     |
-    \\  /    A nd           | www.openfoam.com
-     \\/     M anipulation  |
--------------------------------------------------------------------------------
-    Copyright (C) 2011-2017 OpenFOAM Foundation
-    Copyright (C) 2022 OpenCFD Ltd.
--------------------------------------------------------------------------------
-License
-    This file is part of OpenFOAM.
-
-    OpenFOAM is free software: you can redistribute it and/or modify it
-    under the terms of the GNU General Public License as published by
-    the Free Software Foundation, either version 3 of the License, or
-    (at your option) any later version.
-
-    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
-    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
-    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
-    for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
-
-\*---------------------------------------------------------------------------*/
-
-#include "ProcessorTopology.H"
-#include "ListOps.H"
-#include "Pstream.H"
-#include "commSchedule.H"
-
-// * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
-
-template<class Container, class ProcPatch>
-Foam::labelList Foam::ProcessorTopology<Container, ProcPatch>::procNeighbours
-(
-    const label nProcs,
-    const Container& patches
-)
-{
-    // Determine number of processor neighbours and max neighbour id.
-
-    label nNeighbours = 0;
-
-    label maxNb = 0;
-
-    boolList isNeighbourProc(nProcs, false);
-
-    forAll(patches, patchi)
-    {
-        const auto* cpp = isA<ProcPatch>(patches[patchi]);
-        if (cpp)
-        {
-            const label nbrProci = cpp->neighbProcNo();
-
-            if (!isNeighbourProc[nbrProci])
-            {
-                isNeighbourProc[nbrProci] = true;
-                maxNb = max(maxNb, nbrProci);
-                ++nNeighbours;
-            }
-        }
-    }
-
-    labelList neighbours(nNeighbours, -1);
-
-    nNeighbours = 0;
-
-    forAll(isNeighbourProc, proci)
-    {
-        if (isNeighbourProc[proci])
-        {
-            neighbours[nNeighbours++] = proci;
-        }
-    }
-
-    procPatchMap_.setSize(maxNb + 1);
-    procPatchMap_ = -1;
-
-    forAll(patches, patchi)
-    {
-        const auto* cpp = isA<ProcPatch>(patches[patchi]);
-        if (cpp)
-        {
-            const label nbrProci = cpp->neighbProcNo();
-
-            // Reverse map
-            procPatchMap_[nbrProci] = patchi;
-        }
-    }
-
-    return neighbours;
-}
-
-
-// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
-
-template<class Container, class ProcPatch>
-Foam::ProcessorTopology<Container, ProcPatch>::ProcessorTopology
-(
-    const Container& patches,
-    const label comm
-)
-:
-    labelListList(Pstream::nProcs(comm)),
-    patchSchedule_()
-{
-    if (Pstream::parRun())
-    {
-        // Fill my 'slot' with my neighbours
-        operator[](Pstream::myProcNo(comm)) =
-            procNeighbours(this->size(), patches);
-
-        // Distribute to all processors
-        Pstream::allGatherList(*this, Pstream::msgType(), comm);
-    }
-
-    if
-    (
-        Pstream::parRun()
-     && Pstream::defaultCommsType == Pstream::commsTypes::scheduled
-    )
-    {
-        patchSchedule_.resize(2*patches.size());
-
-        label patchEvali = 0;
-
-        // 1. All non-processor patches
-        // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-        forAll(patches, patchi)
-        {
-            if (!isA<ProcPatch>(patches[patchi]))
-            {
-                patchSchedule_[patchEvali].patch = patchi;
-                patchSchedule_[patchEvali++].init = true;
-                patchSchedule_[patchEvali].patch = patchi;
-                patchSchedule_[patchEvali++].init = false;
-            }
-        }
-
-        // 2. All processor patches
-        // ~~~~~~~~~~~~~~~~~~~~~~~~
-
-        // Determine the schedule for all. Insert processor pair once
-        // to determine the schedule. Each processor pair stands for both
-        // send and receive.
-        label nComms = 0;
-        for (const labelList& neighbours : *this)
-        {
-            nComms += neighbours.size();
-        }
-        DynamicList<labelPair> comms(nComms);
-
-        forAll(*this, proci)
-        {
-            const labelList& neighbours = operator[](proci);
-
-            for (const label nbrProci : neighbours)
-            {
-                if (proci < nbrProci)
-                {
-                    comms.append(labelPair(proci, nbrProci));
-                }
-            }
-        }
-        comms.shrink();
-
-        // Determine a schedule.
-        labelList mySchedule
-        (
-            commSchedule
-            (
-                Pstream::nProcs(comm),
-                comms
-            ).procSchedule()[Pstream::myProcNo(comm)]
-        );
-
-        for (const label commI : mySchedule)
-        {
-            // Get the other processor
-            label nb = comms[commI][0];
-            if (nb == Pstream::myProcNo(comm))
-            {
-                nb = comms[commI][1];
-            }
-            label patchi = procPatchMap_[nb];
-
-            if (Pstream::myProcNo(comm) > nb)
-            {
-                patchSchedule_[patchEvali].patch = patchi;
-                patchSchedule_[patchEvali++].init = true;
-                patchSchedule_[patchEvali].patch = patchi;
-                patchSchedule_[patchEvali++].init = false;
-            }
-            else
-            {
-                patchSchedule_[patchEvali].patch = patchi;
-                patchSchedule_[patchEvali++].init = false;
-                patchSchedule_[patchEvali].patch = patchi;
-                patchSchedule_[patchEvali++].init = true;
-            }
-        }
-    }
-    else
-    {
-        patchSchedule_ = nonBlockingSchedule(patches);
-    }
-}
-
-
-// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
-
-template<class Container, class ProcPatch>
-Foam::lduSchedule
-Foam::ProcessorTopology<Container, ProcPatch>::nonBlockingSchedule
-(
-    const Container& patches
-)
-{
-    lduSchedule patchSchedule(2*patches.size());
-
-    label patchEvali = 0;
-
-    // 1. All non-processor patches
-    // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-    // Have evaluate directly after initEvaluate. Could have them separated
-    // as long as they're not intermingled with processor patches since
-    // then e.g. any reduce parallel traffic would interfere with the
-    // processor swaps.
-
-    forAll(patches, patchi)
-    {
-        if (!isA<ProcPatch>(patches[patchi]))
-        {
-            patchSchedule[patchEvali].patch = patchi;
-            patchSchedule[patchEvali++].init = true;
-            patchSchedule[patchEvali].patch = patchi;
-            patchSchedule[patchEvali++].init = false;
-        }
-    }
-
-    // 2. All processor patches
-    // ~~~~~~~~~~~~~~~~~~~~~~~~
-
-    // 2a. initEvaluate
-    forAll(patches, patchi)
-    {
-        if (isA<ProcPatch>(patches[patchi]))
-        {
-            patchSchedule[patchEvali].patch = patchi;
-            patchSchedule[patchEvali++].init = true;
-        }
-    }
-
-    // 2b. evaluate
-    forAll(patches, patchi)
-    {
-        if (isA<ProcPatch>(patches[patchi]))
-        {
-            patchSchedule[patchEvali].patch = patchi;
-            patchSchedule[patchEvali++].init = false;
-        }
-    }
-
-    return patchSchedule;
-}
-
-
-// ************************************************************************* //
diff --git a/src/OpenFOAM/meshes/ProcessorTopology/ProcessorTopology.H b/src/OpenFOAM/meshes/ProcessorTopology/ProcessorTopology.H
deleted file mode 100644
index 3dbcff1777..0000000000
--- a/src/OpenFOAM/meshes/ProcessorTopology/ProcessorTopology.H
+++ /dev/null
@@ -1,126 +0,0 @@
-/*---------------------------------------------------------------------------*\
-  =========                 |
-  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
-   \\    /   O peration     |
-    \\  /    A nd           | www.openfoam.com
-     \\/     M anipulation  |
--------------------------------------------------------------------------------
-    Copyright (C) 2011-2016 OpenFOAM Foundation
--------------------------------------------------------------------------------
-License
-    This file is part of OpenFOAM.
-
-    OpenFOAM is free software: you can redistribute it and/or modify it
-    under the terms of the GNU General Public License as published by
-    the Free Software Foundation, either version 3 of the License, or
-    (at your option) any later version.
-
-    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
-    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
-    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
-    for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
-
-Class
-    Foam::ProcessorTopology
-
-Description
-    Determines processor-processor connection. After instantiation contains
-    on all processors the processor-processor connection table.
-
-    *this[proci] gives the list of neighbouring processors.
-
-    TODO: This does not currently correctly support multiple processor
-    patches connecting two processors.
-
-SourceFiles
-    ProcessorTopology.C
-
-\*---------------------------------------------------------------------------*/
-
-#ifndef Foam_ProcessorTopology_H
-#define Foam_ProcessorTopology_H
-
-#include "labelList.H"
-#include "lduSchedule.H"
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-namespace Foam
-{
-
-/*---------------------------------------------------------------------------*\
-                       Class ProcessorTopology Declaration
-\*---------------------------------------------------------------------------*/
-
-template<class Container, class ProcPatch>
-class ProcessorTopology
-:
-    public labelListList
-{
-    // Private Data
-
-        //- Local map from neighbour proc to patchi. Different per processor!
-        //  -1 or patchi for connection to procID
-        labelList procPatchMap_;
-
-        //- Order in which the patches should be initialised/evaluated
-        //  corresponding to the schedule
-        lduSchedule patchSchedule_;
-
-
-    // Private Member Functions
-
-        //- Return all neighbouring processors of this processor.
-        //  Sets procPatchMap_.
-        labelList procNeighbours(const label nProcs, const Container&);
-
-public:
-
-    // Constructors
-
-        //- Construct from boundaryMesh
-        ProcessorTopology(const Container& patches, const label comm);
-
-
-    // Static Functions
-
-        //- Calculate non-blocking (i.e. unscheduled) schedule
-        static lduSchedule nonBlockingSchedule(const Container& patches);
-
-
-    // Member Functions
-
-        //- From neighbour processor to index in boundaryMesh.
-        //  Local information (so not same over all processors)
-        const labelList& procPatchMap() const noexcept
-        {
-            return procPatchMap_;
-        }
-
-        //- Order in which the patches should be initialised/evaluated
-        //- corresponding to the schedule
-        const lduSchedule& patchSchedule() const noexcept
-        {
-            return patchSchedule_;
-        }
-};
-
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-} // End namespace Foam
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-#ifdef NoRepository
-    #include "ProcessorTopology.C"
-#endif
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-#endif
-
-// ************************************************************************* //
diff --git a/src/OpenFOAM/meshes/bandCompression/bandCompression.C b/src/OpenFOAM/meshes/bandCompression/bandCompression.C
index f3dfdd16d1..6e43453ffb 100644
--- a/src/OpenFOAM/meshes/bandCompression/bandCompression.C
+++ b/src/OpenFOAM/meshes/bandCompression/bandCompression.C
@@ -31,7 +31,6 @@ License
 #include "CircularBuffer.H"
 #include "CompactListList.H"
 #include "DynamicList.H"
-#include "ListOps.H"  // sortedOrder
 #include "IOstreams.H"
 
 // * * * * * * * * * * * * * * * Local Functions * * * * * * * * * * * * * * //
diff --git a/src/OpenFOAM/meshes/lduMesh/lduPrimitiveMeshTemplates.C b/src/OpenFOAM/meshes/lduMesh/lduPrimitiveMeshTemplates.C
index ed5929d74a..6b774f304f 100644
--- a/src/OpenFOAM/meshes/lduMesh/lduPrimitiveMeshTemplates.C
+++ b/src/OpenFOAM/meshes/lduMesh/lduPrimitiveMeshTemplates.C
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2013 OpenFOAM Foundation
+    Copyright (C) 2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -36,38 +37,37 @@ Foam::lduSchedule Foam::lduPrimitiveMesh::nonBlockingSchedule
 )
 {
     lduSchedule schedule(2*interfaces.size());
-    label slotI = 0;
 
-    forAll(interfaces, i)
+    // 1. All non-processor patches
+    // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+    label patchEvali = 0;
+
+    forAll(interfaces, patchi)
     {
-        if (interfaces.set(i) && !isA<ProcPatch>(interfaces[i]))
+        if (interfaces.set(patchi) && !isA<ProcPatch>(interfaces[patchi]))
         {
-            schedule[slotI].patch = i;
-            schedule[slotI].init = true;
-            slotI++;
-            schedule[slotI].patch = i;
-            schedule[slotI].init = false;
-            slotI++;
+            schedule[patchEvali++].setInitEvaluate(patchi);
+            schedule[patchEvali++].setEvaluate(patchi);
         }
     }
 
-    forAll(interfaces, i)
+    // 2. All processor patches
+    // ~~~~~~~~~~~~~~~~~~~~~~~~
+
+    forAll(interfaces, patchi)
     {
-        if (interfaces.set(i) && isA<ProcPatch>(interfaces[i]))
+        if (interfaces.set(patchi) && isA<ProcPatch>(interfaces[patchi]))
         {
-            schedule[slotI].patch = i;
-            schedule[slotI].init = true;
-            slotI++;
+            schedule[patchEvali++].setInitEvaluate(patchi);
         }
     }
 
-    forAll(interfaces, i)
+    forAll(interfaces, patchi)
     {
-        if (interfaces.set(i) && isA<ProcPatch>(interfaces[i]))
+        if (interfaces.set(patchi) && isA<ProcPatch>(interfaces[patchi]))
         {
-            schedule[slotI].patch = i;
-            schedule[slotI].init = false;
-            slotI++;
+            schedule[patchEvali++].setEvaluate(patchi);
         }
     }
 
diff --git a/src/OpenFOAM/meshes/meshShapes/cell/cellIndList.H b/src/OpenFOAM/meshes/meshShapes/cell/cellIndList.H
index bc584fc14a..29b86927b2 100644
--- a/src/OpenFOAM/meshes/meshShapes/cell/cellIndList.H
+++ b/src/OpenFOAM/meshes/meshShapes/cell/cellIndList.H
@@ -37,13 +37,12 @@ Description
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef cellIndList_H
-#define cellIndList_H
+#ifndef Foam_cellIndList_H
+#define Foam_cellIndList_H
 
 // Include all normal list typedefs as well
 #include "cellList.H"
 #include "IndirectList.H"
-#include "UIndirectList.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
diff --git a/src/OpenFOAM/meshes/meshShapes/cellShape/cellShapeI.H b/src/OpenFOAM/meshes/meshShapes/cellShape/cellShapeI.H
index 9795386b7c..c42938f703 100644
--- a/src/OpenFOAM/meshes/meshShapes/cellShape/cellShapeI.H
+++ b/src/OpenFOAM/meshes/meshShapes/cellShape/cellShapeI.H
@@ -29,7 +29,7 @@ License
 #include "Istream.H"
 #include "cell.H"
 #include "cellModel.H"
-#include "UIndirectList.H"
+#include "IndirectList.H"
 
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
diff --git a/src/OpenFOAM/meshes/meshShapes/edge/edgeIndList.H b/src/OpenFOAM/meshes/meshShapes/edge/edgeIndList.H
index 2d444e9b88..0ad10c3252 100644
--- a/src/OpenFOAM/meshes/meshShapes/edge/edgeIndList.H
+++ b/src/OpenFOAM/meshes/meshShapes/edge/edgeIndList.H
@@ -37,13 +37,12 @@ Description
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef edgeIndList_H
-#define edgeIndList_H
+#ifndef Foam_edgeIndList_H
+#define Foam_edgeIndList_H
 
 // Include all normal list typedefs as well
 #include "edgeList.H"
 #include "IndirectList.H"
-#include "UIndirectList.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
diff --git a/src/OpenFOAM/meshes/meshShapes/face/faceIndList.H b/src/OpenFOAM/meshes/meshShapes/face/faceIndList.H
index 9ae6cf579c..f885a58631 100644
--- a/src/OpenFOAM/meshes/meshShapes/face/faceIndList.H
+++ b/src/OpenFOAM/meshes/meshShapes/face/faceIndList.H
@@ -37,13 +37,12 @@ Description
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef faceIndList_H
-#define faceIndList_H
+#ifndef Foam_faceIndList_H
+#define Foam_faceIndList_H
 
 // Include all normal list typedefs as well
 #include "faceList.H"
 #include "IndirectList.H"
-#include "UIndirectList.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
diff --git a/src/OpenFOAM/meshes/pointMesh/pointPatches/constraint/processor/processorPointPatch.C b/src/OpenFOAM/meshes/pointMesh/pointPatches/constraint/processor/processorPointPatch.C
index 4542912bb8..2190e44f84 100644
--- a/src/OpenFOAM/meshes/pointMesh/pointPatches/constraint/processor/processorPointPatch.C
+++ b/src/OpenFOAM/meshes/pointMesh/pointPatches/constraint/processor/processorPointPatch.C
@@ -30,7 +30,7 @@ License
 #include "addToRunTimeSelectionTable.H"
 #include "pointMesh.H"
 #include "faceList.H"
-#include "primitiveFacePatch.H"
+#include "primitivePatch.H"
 #include "emptyPolyPatch.H"
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
diff --git a/src/OpenFOAM/meshes/polyMesh/globalMeshData/globalMeshData.C b/src/OpenFOAM/meshes/polyMesh/globalMeshData/globalMeshData.C
index 0741da6531..8627307f8d 100644
--- a/src/OpenFOAM/meshes/polyMesh/globalMeshData/globalMeshData.C
+++ b/src/OpenFOAM/meshes/polyMesh/globalMeshData/globalMeshData.C
@@ -27,14 +27,15 @@ License
 \*---------------------------------------------------------------------------*/
 
 #include "globalMeshData.H"
-#include "Pstream.H"
-#include "processorPolyPatch.H"
 #include "globalPoints.H"
 #include "polyMesh.H"
 #include "mapDistribute.H"
 #include "labelIOList.H"
 #include "mergePoints.H"
+#include "processorPolyPatch.H"
+#include "processorTopologyNew.H"
 #include "globalIndexAndTransform.H"
+#include "Pstream.H"
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
@@ -61,15 +62,15 @@ public:
 
 void Foam::globalMeshData::initProcAddr()
 {
-    processorPatchIndices_.setSize(mesh_.boundaryMesh().size());
+    processorPatchIndices_.resize_nocopy(mesh_.boundaryMesh().size());
     processorPatchIndices_ = -1;
 
-    processorPatchNeighbours_.setSize(mesh_.boundaryMesh().size());
+    processorPatchNeighbours_.resize_nocopy(mesh_.boundaryMesh().size());
     processorPatchNeighbours_ = -1;
 
     // Construct processor patch indexing. processorPatchNeighbours_ only
     // set if running in parallel!
-    processorPatches_.setSize(mesh_.boundaryMesh().size());
+    processorPatches_.resize_nocopy(mesh_.boundaryMesh().size());
 
     label nNeighbours = 0;
 
@@ -81,7 +82,7 @@ void Foam::globalMeshData::initProcAddr()
             processorPatchIndices_[patchi] = nNeighbours++;
         }
     }
-    processorPatches_.setSize(nNeighbours);
+    processorPatches_.resize(nNeighbours);
 
 
     if (Pstream::parRun())
@@ -1728,14 +1729,21 @@ void Foam::globalMeshData::calcGlobalCoPointSlaves() const
 
 Foam::globalMeshData::globalMeshData(const polyMesh& mesh)
 :
-    processorTopology(mesh.boundaryMesh(), UPstream::worldComm),
     mesh_(mesh),
     nTotalPoints_(-1),
     nTotalFaces_(-1),
     nTotalCells_(-1),
-    processorPatches_(0),
-    processorPatchIndices_(0),
-    processorPatchNeighbours_(0),
+    processorTopology_
+    (
+        processorTopology::New<processorPolyPatch>
+        (
+            mesh.boundaryMesh(),
+            UPstream::worldComm
+        )
+    ),
+    processorPatches_(),
+    processorPatchIndices_(),
+    processorPatchNeighbours_(),
     nGlobalPoints_(-1),
     sharedPointLabelsPtr_(nullptr),
     sharedPointAddrPtr_(nullptr),
@@ -1750,10 +1758,9 @@ Foam::globalMeshData::globalMeshData(const polyMesh& mesh)
 
 // * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
 
+// A non-default destructor since we had incomplete types in the header
 Foam::globalMeshData::~globalMeshData()
-{
-    clearOut();
-}
+{}
 
 
 void Foam::globalMeshData::clearOut()
@@ -1780,6 +1787,7 @@ void Foam::globalMeshData::clearOut()
     globalPointSlavesPtr_.clear();
     globalPointTransformedSlavesPtr_.clear();
     globalPointSlavesMapPtr_.clear();
+
     // Edge
     globalEdgeNumberingPtr_.clear();
     globalEdgeSlavesPtr_.clear();
@@ -2728,7 +2736,7 @@ void Foam::globalMeshData::updateMesh()
 
     if (debug)
     {
-        Pout<< "globalMeshData : nTotalFaces_:" << nTotalFaces_ << endl;
+        Pout<< "globalMeshData : nTotalFaces:" << nTotalFaces_ << endl;
     }
 
     nTotalCells_ = returnReduce
@@ -2741,7 +2749,7 @@ void Foam::globalMeshData::updateMesh()
 
     if (debug)
     {
-        Pout<< "globalMeshData : nTotalCells_:" << nTotalCells_ << endl;
+        Pout<< "globalMeshData : nTotalCells:" << nTotalCells_ << endl;
     }
 
     nTotalPoints_ = returnReduce
@@ -2757,7 +2765,7 @@ void Foam::globalMeshData::updateMesh()
 
     if (debug)
     {
-        Pout<< "globalMeshData : nTotalPoints_:" << nTotalPoints_ << endl;
+        Pout<< "globalMeshData : nTotalPoints:" << nTotalPoints_ << endl;
     }
 }
 
diff --git a/src/OpenFOAM/meshes/polyMesh/globalMeshData/globalMeshData.H b/src/OpenFOAM/meshes/polyMesh/globalMeshData/globalMeshData.H
index 41ed3e36fb..fb75f9677e 100644
--- a/src/OpenFOAM/meshes/polyMesh/globalMeshData/globalMeshData.H
+++ b/src/OpenFOAM/meshes/polyMesh/globalMeshData/globalMeshData.H
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2018-2021 OpenCFD Ltd.
+    Copyright (C) 2018-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -81,8 +81,8 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef globalMeshData_H
-#define globalMeshData_H
+#ifndef Foam_globalMeshData_H
+#define Foam_globalMeshData_H
 
 #include "processorTopology.H"
 #include "labelPair.H"
@@ -106,8 +106,6 @@ class bitSet;
 \*---------------------------------------------------------------------------*/
 
 class globalMeshData
-:
-    public processorTopology
 {
     // Private Data
 
@@ -129,6 +127,9 @@ class globalMeshData
 
         // Processor patch addressing (be careful if not running in parallel!)
 
+            //- The processor/processor topology
+            processorTopology processorTopology_;
+
             //- List of processor patch labels
             //  (size of list = number of processor patches)
             labelList processorPatches_;
@@ -377,6 +378,19 @@ public:
 
         // Processor patch addressing (be careful when not running in parallel)
 
+            //- The processor to processor topology.
+            const processorTopology& topology() const noexcept
+            {
+                return processorTopology_;
+            }
+
+            //- Order in which the patches should be initialised/evaluated
+            //- corresponding to the schedule
+            const lduSchedule& patchSchedule() const noexcept
+            {
+                return processorTopology_.patchSchedule();
+            }
+
             //- Return list of processor patch labels
             //  (size of list = number of processor patches)
             const labelList& processorPatches() const noexcept
@@ -393,7 +407,7 @@ public:
             }
 
             //- Return processorPatchIndices of the neighbours
-            //  processor patches. -1 if not running parallel.
+            //- processor patches. -1 if not running parallel.
             const labelList& processorPatchNeighbours() const noexcept
             {
                 return processorPatchNeighbours_;
diff --git a/src/OpenFOAM/meshes/polyMesh/globalMeshData/processorTopology.H b/src/OpenFOAM/meshes/polyMesh/globalMeshData/processorTopology.H
deleted file mode 100644
index 950f2d1e4f..0000000000
--- a/src/OpenFOAM/meshes/polyMesh/globalMeshData/processorTopology.H
+++ /dev/null
@@ -1,51 +0,0 @@
-/*---------------------------------------------------------------------------*\
-  =========                 |
-  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
-   \\    /   O peration     |
-    \\  /    A nd           | www.openfoam.com
-     \\/     M anipulation  |
--------------------------------------------------------------------------------
-    Copyright (C) 2011-2013 OpenFOAM Foundation
--------------------------------------------------------------------------------
-License
-    This file is part of OpenFOAM.
-
-    OpenFOAM is free software: you can redistribute it and/or modify it
-    under the terms of the GNU General Public License as published by
-    the Free Software Foundation, either version 3 of the License, or
-    (at your option) any later version.
-
-    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
-    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
-    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
-    for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
-
-\*---------------------------------------------------------------------------*/
-
-#ifndef processorTopology_H
-#define processorTopology_H
-
-#include "ProcessorTopology.H"
-#include "processorPolyPatch.H"
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-namespace Foam
-{
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-typedef ProcessorTopology<polyPatchList, processorPolyPatch> processorTopology;
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-} // End namespace Foam
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-#endif
-
-// ************************************************************************* //
diff --git a/src/OpenFOAM/meshes/polyMesh/mapPolyMesh/mapDistribute/IOmapDistributePolyMesh.C b/src/OpenFOAM/meshes/polyMesh/mapPolyMesh/mapDistribute/IOmapDistributePolyMesh.C
index 2af120a3d0..ab1b4be762 100644
--- a/src/OpenFOAM/meshes/polyMesh/mapPolyMesh/mapDistribute/IOmapDistributePolyMesh.C
+++ b/src/OpenFOAM/meshes/polyMesh/mapPolyMesh/mapDistribute/IOmapDistributePolyMesh.C
@@ -106,17 +106,59 @@ Foam::IOmapDistributePolyMesh::IOmapDistributePolyMesh
 }
 
 
+Foam::IOmapDistributePolyMeshRef::IOmapDistributePolyMeshRef
+(
+    const IOobject& io,
+    const mapDistributePolyMesh& map
+)
+:
+    regIOobject(io),
+    contentRef_(map)  // cref
+{}
+
+
+// Not sure if we need this yet...
+//
+/// Foam::IOmapDistributePolyMeshRef::IOmapDistributePolyMeshRef
+/// (
+///     const IOobject& io,
+///     mapDistributePolyMesh& map
+/// )
+/// :
+///     regIOobject(io),
+///     contentRef_()
+/// {
+///     contentRef_.ref(map);  // writable reference
+/// }
+
+
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
 bool Foam::IOmapDistributePolyMesh::readData(Istream& is)
 {
-    return (is >> *this).good();
+    is >> *this;
+    return is.good();
 }
 
 
 bool Foam::IOmapDistributePolyMesh::writeData(Ostream& os) const
 {
-    return (os << *this).good();
+    os << *this;
+    return os.good();
+}
+
+
+bool Foam::IOmapDistributePolyMeshRef::readData(Istream& is)
+{
+    is >> contentRef_.ref();
+    return is.good();
+}
+
+
+bool Foam::IOmapDistributePolyMeshRef::writeData(Ostream& os) const
+{
+    os << contentRef_.cref();
+    return os.good();
 }
 
 
diff --git a/src/OpenFOAM/meshes/polyMesh/mapPolyMesh/mapDistribute/IOmapDistributePolyMesh.H b/src/OpenFOAM/meshes/polyMesh/mapPolyMesh/mapDistribute/IOmapDistributePolyMesh.H
index 46d326006e..a3afb0f245 100644
--- a/src/OpenFOAM/meshes/polyMesh/mapPolyMesh/mapDistribute/IOmapDistributePolyMesh.H
+++ b/src/OpenFOAM/meshes/polyMesh/mapPolyMesh/mapDistribute/IOmapDistributePolyMesh.H
@@ -42,6 +42,7 @@ SourceFiles
 
 #include "mapDistributePolyMesh.H"
 #include "regIOobject.H"
+#include "refPtr.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
@@ -102,6 +103,74 @@ public:
 };
 
 
+/*---------------------------------------------------------------------------*\
+                 Class IOmapDistributePolyMeshRef Declaration
+\*---------------------------------------------------------------------------*/
+
+//- A IOmapDistributePolyMesh wrapper for using referenced external data.
+class IOmapDistributePolyMeshRef
+:
+    public regIOobject
+{
+    // Private Data
+
+        //- Reference to the external content
+        refPtr<mapDistributePolyMesh> contentRef_;
+
+public:
+
+    //- Type is identical to IOmapDistributePolyMesh
+    virtual const word& type() const
+    {
+        return IOmapDistributePolyMesh::typeName;
+    }
+
+
+    // Generated Methods
+
+        //- No default construct
+        IOmapDistributePolyMeshRef() = delete;
+
+        //- No copy construct
+        IOmapDistributePolyMeshRef(const IOmapDistributePolyMeshRef&) = delete;
+
+        //- No copy assignment
+        void operator=(const IOmapDistributePolyMeshRef&) = delete;
+
+
+    // Constructors
+
+        //- Construct from IOobject and const data reference
+        IOmapDistributePolyMeshRef
+        (
+            const IOobject& io,
+            const mapDistributePolyMesh& map
+        );
+
+
+    //- Destructor
+    virtual ~IOmapDistributePolyMeshRef() = default;
+
+
+    // Member Functions
+
+        //- Allow cast to const content
+        //  Fatal if content is not set
+        operator const mapDistributePolyMesh&() const
+        {
+            return contentRef_.cref();
+        }
+
+        //- The readData method for regIOobject read operation
+        //  Fatal if content is constant (or not set)
+        virtual bool readData(Istream& is);
+
+        //- The writeData method for regIOobject write operation
+        //  Fatal if content is not set
+        virtual bool writeData(Ostream& os) const;
+};
+
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 } // End namespace Foam
diff --git a/src/OpenFOAM/meshes/polyMesh/zones/faceZone/faceZone.H b/src/OpenFOAM/meshes/polyMesh/zones/faceZone/faceZone.H
index ea247d84db..dc9c2019da 100644
--- a/src/OpenFOAM/meshes/polyMesh/zones/faceZone/faceZone.H
+++ b/src/OpenFOAM/meshes/polyMesh/zones/faceZone/faceZone.H
@@ -40,12 +40,12 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef faceZone_H
-#define faceZone_H
+#ifndef Foam_faceZone_H
+#define Foam_faceZone_H
 
 #include "zone.H"
 #include "faceZoneMeshFwd.H"
-#include "primitiveFacePatch.H"
+#include "primitivePatch.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
diff --git a/src/OpenFOAM/meshes/primitiveMesh/primitivePatch/indirectPrimitivePatch.H b/src/OpenFOAM/meshes/primitiveMesh/primitivePatch/indirectPrimitivePatch.H
index 8363ce8f83..4de24fb4b2 100644
--- a/src/OpenFOAM/meshes/primitiveMesh/primitivePatch/indirectPrimitivePatch.H
+++ b/src/OpenFOAM/meshes/primitiveMesh/primitivePatch/indirectPrimitivePatch.H
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011 OpenFOAM Foundation
-    Copyright (C) 2020 OpenCFD Ltd.
+    Copyright (C) 2020-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -28,13 +28,20 @@ Typedef
     Foam::indirectPrimitivePatch
 
 Description
-    A PrimitivePatch with an IndirectList for the faces, const reference
-    for the point field.
+    A PrimitivePatch with an IndirectList for the faces,
+    const reference for the point field.
+
+Typedef
+    Foam::uindirectPrimitivePatch
+
+Description
+    A PrimitivePatch with UIndirectList for the faces,
+    const reference for the point field.
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef indirectPrimitivePatch_H
-#define indirectPrimitivePatch_H
+#ifndef Foam_indirectPrimitivePatch_H
+#define Foam_indirectPrimitivePatch_H
 
 #include "PrimitivePatch.H"
 #include "face.H"
@@ -45,8 +52,15 @@ Description
 
 namespace Foam
 {
-    typedef PrimitivePatch<IndirectList<face>, const pointField&>
-        indirectPrimitivePatch;
+
+typedef
+    PrimitivePatch<IndirectList<face>, const pointField&>
+    indirectPrimitivePatch;
+
+typedef
+    PrimitivePatch<UIndirectList<face>, const pointField&>
+    uindirectPrimitivePatch;
+
 }
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
diff --git a/src/OpenFOAM/meshes/primitiveMesh/primitivePatch/primitiveFacePatch.H b/src/OpenFOAM/meshes/primitiveMesh/primitivePatch/primitiveFacePatch.H
index a84f122510..b753c0b2b6 100644
--- a/src/OpenFOAM/meshes/primitiveMesh/primitivePatch/primitiveFacePatch.H
+++ b/src/OpenFOAM/meshes/primitiveMesh/primitivePatch/primitiveFacePatch.H
@@ -1,57 +1,16 @@
 /*---------------------------------------------------------------------------*\
-  =========                 |
-  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
-   \\    /   O peration     |
-    \\  /    A nd           | www.openfoam.com
-     \\/     M anipulation  |
--------------------------------------------------------------------------------
-    Copyright (C) 2011 OpenFOAM Foundation
-    Copyright (C) 2020 OpenCFD Ltd.
--------------------------------------------------------------------------------
-License
-    This file is part of OpenFOAM.
-
-    OpenFOAM is free software: you can redistribute it and/or modify it
-    under the terms of the GNU General Public License as published by
-    the Free Software Foundation, either version 3 of the License, or
-    (at your option) any later version.
-
-    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
-    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
-    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
-    for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
-
-Typedef
-    Foam::primitiveFacePatch
-
 Description
-    A PrimitivePatch with List storage for the faces,
-    const reference for the point field.
+    Compatibility include
 
-    Can be used to store faces.
+    primitiveFacePatch.H combined into primitivePatch.H
+    (MAY-2022)
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef primitiveFacePatch_H
-#define primitiveFacePatch_H
+#ifndef Foam_primitiveFacePatch_H
+#define Foam_primitiveFacePatch_H
 
-#include "PrimitivePatch.H"
-#include "face.H"
-#include "List.H"
-#include "pointField.H"
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-namespace Foam
-{
-    typedef PrimitivePatch<List<face>, const pointField&>
-        primitiveFacePatch;
-}
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+#include "indirectPrimitivePatch.H"
 
 #endif
 
diff --git a/src/OpenFOAM/meshes/primitiveMesh/primitivePatch/primitivePatch.H b/src/OpenFOAM/meshes/primitiveMesh/primitivePatch/primitivePatch.H
index 4d811d2204..9fda6d684f 100644
--- a/src/OpenFOAM/meshes/primitiveMesh/primitivePatch/primitivePatch.H
+++ b/src/OpenFOAM/meshes/primitiveMesh/primitivePatch/primitivePatch.H
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011 OpenFOAM Foundation
-    Copyright (C) 2020 OpenCFD Ltd.
+    Copyright (C) 2020-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -28,27 +28,43 @@ Typedef
     Foam::primitivePatch
 
 Description
-    A PrimitivePatch with a SubList addressing for the faces,
+    A PrimitivePatch with a SubList \em addressing for the faces,
     const reference for the point field.
 
     Can be used as addressing for a faceList slice.
 
+Typedef
+    Foam::primitiveFacePatch
+
+Description
+    A PrimitivePatch with List \em storage for the faces,
+    const reference for the point field.
+
+    Can be used to store faces.
+
 \*---------------------------------------------------------------------------*/
 
-#ifndef primitivePatch_H
-#define primitivePatch_H
+#ifndef Foam_primitivePatch_H
+#define Foam_primitivePatch_H
 
 #include "PrimitivePatch.H"
 #include "face.H"
 #include "SubList.H"
+#include "List.H"
 #include "pointField.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 namespace Foam
 {
-    typedef PrimitivePatch<SubList<face>, const pointField&>
-        primitivePatch;
+
+typedef
+    PrimitivePatch<SubList<face>, const pointField&>
+    primitivePatch;
+
+typedef
+    PrimitivePatch<List<face>, const pointField&>
+    primitiveFacePatch;
 }
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
diff --git a/src/OpenFOAM/meshes/primitiveMesh/primitivePatch/uindirectPrimitivePatch.H b/src/OpenFOAM/meshes/primitiveMesh/primitivePatch/uindirectPrimitivePatch.H
index 15e6de830d..8660ca9087 100644
--- a/src/OpenFOAM/meshes/primitiveMesh/primitivePatch/uindirectPrimitivePatch.H
+++ b/src/OpenFOAM/meshes/primitiveMesh/primitivePatch/uindirectPrimitivePatch.H
@@ -1,55 +1,16 @@
 /*---------------------------------------------------------------------------*\
-  =========                 |
-  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
-   \\    /   O peration     |
-    \\  /    A nd           | www.openfoam.com
-     \\/     M anipulation  |
--------------------------------------------------------------------------------
-    Copyright (C) 2011 OpenFOAM Foundation
-    Copyright (C) 2020 OpenCFD Ltd.
--------------------------------------------------------------------------------
-License
-    This file is part of OpenFOAM.
-
-    OpenFOAM is free software: you can redistribute it and/or modify it
-    under the terms of the GNU General Public License as published by
-    the Free Software Foundation, either version 3 of the License, or
-    (at your option) any later version.
-
-    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
-    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
-    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
-    for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
-
-Typedef
-    Foam::uindirectPrimitivePatch
-
 Description
-    A PrimitivePatch with UIndirectList for the faces, const reference
-    for the point field.
+    Compatibility include
+
+    uindirectPrimitivePatch.H combined into uindirectPrimitivePatch.H
+    (MAY-2022)
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef uindirectPrimitivePatch_H
-#define uindirectPrimitivePatch_H
+#ifndef Foam_uindirectPrimitivePatch_H
+#define Foam_uindirectPrimitivePatch_H
 
-#include "PrimitivePatch.H"
-#include "face.H"
-#include "UIndirectList.H"
-#include "pointField.H"
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-namespace Foam
-{
-    typedef PrimitivePatch<UIndirectList<face>, const pointField&>
-        uindirectPrimitivePatch;
-}
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+#include "indirectPrimitivePatch.H"
 
 #endif
 
diff --git a/src/OpenFOAM/meshes/primitiveShapes/point/pointIndList.H b/src/OpenFOAM/meshes/primitiveShapes/point/pointIndList.H
index 5a865aeb82..aa564e7f82 100644
--- a/src/OpenFOAM/meshes/primitiveShapes/point/pointIndList.H
+++ b/src/OpenFOAM/meshes/primitiveShapes/point/pointIndList.H
@@ -37,13 +37,12 @@ Description
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef pointIndList_H
-#define pointIndList_H
+#ifndef Foam_pointIndList_H
+#define Foam_pointIndList_H
 
 // Include all normal list typedefs as well
 #include "pointList.H"
 #include "IndirectList.H"
-#include "UIndirectList.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
diff --git a/src/OpenFOAM/parallel/commSchedule/commSchedule.C b/src/OpenFOAM/parallel/commSchedule/commSchedule.C
index 6bb6d5949b..32302b39fb 100644
--- a/src/OpenFOAM/parallel/commSchedule/commSchedule.C
+++ b/src/OpenFOAM/parallel/commSchedule/commSchedule.C
@@ -90,7 +90,8 @@ Foam::commSchedule::commSchedule
         if (proc0 < 0 || proc0 >= nProcs || proc1 < 0 || proc1 >= nProcs)
         {
             FatalErrorInFunction
-                << "Illegal processor " << comms[commI] << abort(FatalError);
+                << "Illegal processor(s): "
+                << comms[commI] << abort(FatalError);
         }
 
         procToComms[proc0].append(commI);
diff --git a/src/OpenFOAM/parallel/commSchedule/commSchedule.H b/src/OpenFOAM/parallel/commSchedule/commSchedule.H
index 765f4165ff..821dfa9afc 100644
--- a/src/OpenFOAM/parallel/commSchedule/commSchedule.H
+++ b/src/OpenFOAM/parallel/commSchedule/commSchedule.H
@@ -42,8 +42,8 @@ Description
       - procSchedule()[proci] gives per proci
 
     Does not care whether 'talking' is first send, second receive or maybe
-    full swap. This is all responsibility of caller. See ProcessorTopology
-    class for use in scheduling processor boundary swaps.
+    full swap. This is all responsibility of caller.
+    See Foam::rocessorTopology for use in scheduling processor boundary swaps.
 
 SourceFiles
     commSchedule.C
@@ -78,13 +78,17 @@ class commSchedule
 
 public:
 
+    //- Runtime type information
     ClassName("commSchedule");
 
+
     // Constructors
 
         //- Construct from wanted communication. Wanted communication is between
-        //  two processors. Can be a one-way communication or
-        //  two-way communication, that is up to the caller. This class just
+        //- two processors. Can be a one-way communication or
+        //- two-way communication, that is up to the caller.
+        //
+        //  This class just
         //  determines an order for it such that any processor is only talking
         //  to one other at a time. After construction:
         //  - schedule is the order in which comms is done.
diff --git a/src/OpenFOAM/parallel/processorTopology/processorTopology.H b/src/OpenFOAM/parallel/processorTopology/processorTopology.H
new file mode 100644
index 0000000000..3cce0ec109
--- /dev/null
+++ b/src/OpenFOAM/parallel/processorTopology/processorTopology.H
@@ -0,0 +1,176 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2011-2016 OpenFOAM Foundation
+    Copyright (C) 2022 OpenCFD Ltd.
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+Class
+    Foam::processorTopology
+
+Description
+    Determines/represents processor-processor connection.
+    After instantiation contains the processor-processor connection table
+    (globally synchronized on all processors).
+
+Note
+    A processorTopology is usually generated by using the \c New
+    factory method, which has been wrapped into a separate header to
+    minimize dependencies.
+
+Warning
+    Does not currently correctly support multiple processor
+    patches connecting two processors.
+
+SourceFiles
+    processorTopologyNew.H
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef Foam_processorTopology_H
+#define Foam_processorTopology_H
+
+#include "labelList.H"
+#include "lduSchedule.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+/*---------------------------------------------------------------------------*\
+                      Class processorTopology Declaration
+\*---------------------------------------------------------------------------*/
+
+class processorTopology
+{
+    // Private Data
+
+        //- The processor to processor connection (adjacency) table
+        labelListList procNeighbours_;
+
+        //- Order in which the patches should be initialised/evaluated
+        //- corresponding to the schedule
+        lduSchedule patchSchedule_;
+
+        //- Local map from neighbour proc to patchi. Different per processor!
+        //  -1 or patchi for connection to procID
+        labelList procPatchMap_;
+
+
+    // Private Member Functions
+
+        //- From neighbour processor to index in our local boundary.
+        //  Local information (so not same over all processors)
+        ///const labelList& procPatchMap() const noexcept
+        ///{
+        ///    return procPatchMap_;
+        ///}
+
+        //- Which \em local boundary is attached to specified processor
+        //  Local information (so not same over all processors)
+        //  \return -1 if not currently connected to specified processor.
+        label procToLocalPatch(const label proci) const
+        {
+            return
+            (
+                proci >= 0 && proci < procPatchMap_.size()
+              ? procPatchMap_[proci]
+              : static_cast<label>(-1)
+            );
+        }
+
+
+public:
+
+    // Generated Methods
+
+        //- Default construct (empty)
+        processorTopology() = default;
+
+        //- Copy construct
+        processorTopology(const processorTopology&) = default;
+
+        //- Move construct
+        processorTopology(processorTopology&&) = default;
+
+        //- Copy assignment
+        processorTopology& operator=(const processorTopology&) = default;
+
+        //- Move assignment
+        processorTopology& operator=(processorTopology&&) = default;
+
+
+    // Static Functions
+
+        //- Factory method to create topology, schedule and proc/patch maps.
+        //  Scans the list of patches for processor connections corresponding
+        //  to the ProcPatch type.
+        template<class ProcPatch, class PatchListType>
+        static processorTopology New
+        (
+            const PatchListType& patches,
+            const label comm
+        );
+
+
+    // Member Functions
+
+        //- The number of processors used by the topology
+        label nProcs() const noexcept
+        {
+            return procNeighbours_.size();
+        }
+
+        //- The processor to processor connection topology
+        //- (like an adjacency list). Globally synchronized information
+        const labelListList& procNeighbours() const noexcept
+        {
+            return procNeighbours_;
+        }
+
+        //- Order in which the patches should be initialised/evaluated
+        //- corresponding to the schedule
+        const lduSchedule& patchSchedule() const noexcept
+        {
+            return patchSchedule_;
+        }
+
+        //- Which \em local boundary is attached to specified processor
+        //  Local information (so not same over all processors)
+        //  \return -1 if not currently connected to specified processor.
+        label procPatchLookup(const label proci) const
+        {
+            return procToLocalPatch(proci);
+        }
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //
diff --git a/src/OpenFOAM/parallel/processorTopology/processorTopologyNew.H b/src/OpenFOAM/parallel/processorTopology/processorTopologyNew.H
new file mode 100644
index 0000000000..e7f966143a
--- /dev/null
+++ b/src/OpenFOAM/parallel/processorTopology/processorTopologyNew.H
@@ -0,0 +1,229 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2011-2017 OpenFOAM Foundation
+    Copyright (C) 2022 OpenCFD Ltd.
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+InClass
+    Foam::processorTopology
+
+Description
+    Define the processor-processor connection table by walking a list of
+    patches and detecting the processor ones.
+
+    This has been split off as a separate include from processorTopology
+    to minimize dependencies.
+
+Warning
+    Does not currently correctly support multiple processor
+    patches connecting two processors.
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef Foam_processorTopologyNew_H
+#define Foam_processorTopologyNew_H
+
+#include "processorTopology.H"
+#include "bitSet.H"
+#include "commSchedule.H"
+#include "DynamicList.H"
+#include "Pstream.H"
+
+// * * * * * * * * * * * * * Static Member Functions * * * * * * * * * * * * //
+
+template<class ProcPatch, class PatchListType>
+Foam::processorTopology Foam::processorTopology::New
+(
+    const PatchListType& patches,
+    const label comm
+)
+{
+    const label myProci = Pstream::myProcNo(comm);
+    const label nProcs = Pstream::nProcs(comm);
+
+    processorTopology procTopo;
+
+    auto& procToProcs = procTopo.procNeighbours_;
+    auto& procToPatch = procTopo.procPatchMap_;
+    auto& schedule = procTopo.patchSchedule_;
+
+    procToProcs.resize(nProcs);
+    schedule.resize(2*patches.size());
+
+
+    if (Pstream::parRun())
+    {
+        // Fill my 'slot' with my neighbours
+        auto& procSlot = procToProcs[myProci];
+
+        bitSet isNeighbour(procToProcs.size());
+
+        forAll(patches, patchi)
+        {
+            const auto* cpp = isA<ProcPatch>(patches[patchi]);
+            if (cpp)
+            {
+                const label nbrProci = cpp->neighbProcNo();
+
+                isNeighbour.set(nbrProci);
+            }
+        }
+
+        // The neighbouring procs in sorted (ascending) order
+        procSlot = isNeighbour.sortedToc();
+
+        const label maxNbrProci = procSlot.empty() ? -1 : procSlot.last();
+
+        // Note could also use Map<label> if desired
+        procToPatch.resize_nocopy(maxNbrProci + 1);
+        procToPatch = -1;
+
+        forAll(patches, patchi)
+        {
+            const auto* cpp = isA<ProcPatch>(patches[patchi]);
+            if (cpp)
+            {
+                const label nbrProci = cpp->neighbProcNo();
+
+                // Reverse map
+                procToPatch[nbrProci] = patchi;
+            }
+        }
+
+        // Synchronize on all processors
+        Pstream::allGatherList(procToProcs, UPstream::msgType(), comm);
+    }
+
+
+    // Define the schedule
+
+    label patchEvali = 0;
+
+    // 1. All non-processor patches
+    // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+    forAll(patches, patchi)
+    {
+        if (!isA<ProcPatch>(patches[patchi]))
+        {
+            schedule[patchEvali++].setInitEvaluate(patchi);
+            schedule[patchEvali++].setEvaluate(patchi);
+        }
+    }
+
+
+    // 2. All processor patches
+    // ~~~~~~~~~~~~~~~~~~~~~~~~
+
+    if
+    (
+        Pstream::parRun()
+     && Pstream::defaultCommsType == Pstream::commsTypes::scheduled
+    )
+    {
+        // Determine the schedule for all processor patches.
+        // Insert processor pair once to determine the schedule.
+        // Each processor pair stands for both send and receive.
+
+        label nComms = 0;
+        for (const labelList& nbrProcs : procToProcs)
+        {
+            nComms += nbrProcs.size();
+        }
+        DynamicList<labelPair> comms(nComms/2);
+
+        forAll(procToProcs, proci)
+        {
+            for (const label nbrProci : procToProcs[proci])
+            {
+                if (proci < nbrProci)
+                {
+                    comms.append(labelPair(proci, nbrProci));
+                }
+            }
+        }
+
+        // Determine a schedule.
+        labelList mySchedule
+        (
+            commSchedule
+            (
+                nProcs,
+                comms
+            ).procSchedule()[myProci]
+        );
+
+        for (const label scheduleIndex : mySchedule)
+        {
+            // Get the other processor
+            label nbrProci = comms[scheduleIndex][0];
+            if (nbrProci == myProci)
+            {
+                nbrProci = comms[scheduleIndex][1];
+            }
+            const label patchi = procToPatch[nbrProci];
+
+            if (myProci > nbrProci)
+            {
+                schedule[patchEvali++].setInitEvaluate(patchi);
+                schedule[patchEvali++].setEvaluate(patchi);
+            }
+            else
+            {
+                schedule[patchEvali++].setEvaluate(patchi);
+                schedule[patchEvali++].setInitEvaluate(patchi);
+            }
+        }
+    }
+    else
+    {
+        // Non-blocking schedule for processor patches
+
+        // initEvaluate
+        forAll(patches, patchi)
+        {
+            if (isA<ProcPatch>(patches[patchi]))
+            {
+                schedule[patchEvali++].setInitEvaluate(patchi);
+            }
+        }
+
+        // evaluate
+        forAll(patches, patchi)
+        {
+            if (isA<ProcPatch>(patches[patchi]))
+            {
+                schedule[patchEvali++].setEvaluate(patchi);
+            }
+        }
+    }
+
+    return procTopo;
+}
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //
diff --git a/src/OpenFOAM/primitives/Scalar/lists/scalarIndList.H b/src/OpenFOAM/primitives/Scalar/lists/scalarIndList.H
index f2243ffc75..5fa0b3c80c 100644
--- a/src/OpenFOAM/primitives/Scalar/lists/scalarIndList.H
+++ b/src/OpenFOAM/primitives/Scalar/lists/scalarIndList.H
@@ -37,13 +37,12 @@ Description
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef scalarIndList_H
-#define scalarIndList_H
+#ifndef Foam_scalarIndList_H
+#define Foam_scalarIndList_H
 
 // Include all normal list typedefs as well
 #include "scalarList.H"
 #include "IndirectList.H"
-#include "UIndirectList.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
diff --git a/src/OpenFOAM/primitives/Vector/lists/vectorIndList.H b/src/OpenFOAM/primitives/Vector/lists/vectorIndList.H
index 0d2e9d485d..16e24a46b1 100644
--- a/src/OpenFOAM/primitives/Vector/lists/vectorIndList.H
+++ b/src/OpenFOAM/primitives/Vector/lists/vectorIndList.H
@@ -37,13 +37,12 @@ Description
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef vectorIndList_H
-#define vectorIndList_H
+#ifndef Foam_vectorIndList_H
+#define Foam_vectorIndList_H
 
 // Include all normal list typedefs as well
 #include "vectorList.H"
 #include "IndirectList.H"
-#include "UIndirectList.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
diff --git a/src/OpenFOAM/primitives/ints/lists/labelIndList.H b/src/OpenFOAM/primitives/ints/lists/labelIndList.H
index 56ad93c856..da2bfb50a6 100644
--- a/src/OpenFOAM/primitives/ints/lists/labelIndList.H
+++ b/src/OpenFOAM/primitives/ints/lists/labelIndList.H
@@ -43,14 +43,13 @@ Description
 // Include all normal list typedefs as well
 #include "labelList.H"
 #include "IndirectList.H"
-#include "UIndirectList.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 namespace Foam
 {
-    // NB: labelUIndList is defined in UIndirectList itself
     typedef IndirectList<label>  labelIndList;
+    // labelUIndList is defined in UIndirectList itself
 }
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
diff --git a/src/OpenFOAM/primitives/strings/lists/stringListOps.H b/src/OpenFOAM/primitives/strings/lists/stringListOps.H
index 18a769da2b..43d855d102 100644
--- a/src/OpenFOAM/primitives/strings/lists/stringListOps.H
+++ b/src/OpenFOAM/primitives/strings/lists/stringListOps.H
@@ -70,6 +70,7 @@ namespace Foam
     //  \endcode
     //
     //  \return List indices for matching strings
+    //  \see IndirectList::subset_if
     template<class UnaryMatchPredicate, class StringType>
     labelList findMatchingStrings
     (
@@ -161,6 +162,7 @@ namespace Foam
     //  \code
     //    subsetMatchingStrings<regExp, stringList>(myRegExp, list);
     //  \endcode
+    //  \see IndirectList::subset_if
     template<class UnaryMatchPredicate, class StringListType>
     StringListType subsetMatchingStrings
     (
@@ -326,8 +328,6 @@ namespace Foam
     }
 
 
-
-
 /*---------------------------------------------------------------------------*\
                       Namespace stringListOps Declaration
 \*---------------------------------------------------------------------------*/
diff --git a/src/conversion/ccm/reader/ccmReaderMesh.C b/src/conversion/ccm/reader/ccmReaderMesh.C
index e7bd28a3cd..ca38f19d1f 100644
--- a/src/conversion/ccm/reader/ccmReaderMesh.C
+++ b/src/conversion/ccm/reader/ccmReaderMesh.C
@@ -34,7 +34,7 @@ License
 #include "IOdictionary.H"
 
 #include "ccmBoundaryInfo.H"
-#include "uindirectPrimitivePatch.H"
+#include "indirectPrimitivePatch.H"
 #include "SortableList.H"
 #include "mergePoints.H"
 #include "bitSet.H"
diff --git a/src/conversion/vtk/output/foamVtkIndPatchGeoFieldsWriter.H b/src/conversion/vtk/output/foamVtkIndPatchGeoFieldsWriter.H
index 6f4691d0cf..aecd1defc8 100644
--- a/src/conversion/vtk/output/foamVtkIndPatchGeoFieldsWriter.H
+++ b/src/conversion/vtk/output/foamVtkIndPatchGeoFieldsWriter.H
@@ -31,6 +31,14 @@ Description
     as a vtp file or a legacy vtk file
     with support for geometric fields.
 
+Typedef
+    Foam::vtk::uindirectPatchGeoFieldsWriter
+
+Description
+    Write uindirectPrimitivePatch faces/points
+    as a vtp file or a legacy vtk file
+    with support for geometric fields.
+
 See Also
     Foam::vtk::GenericPatchWriter
 
@@ -55,6 +63,10 @@ typedef
     GenericPatchGeoFieldsWriter<indirectPrimitivePatch>
     indirectPatchGeoFieldsWriter;
 
+typedef
+    GenericPatchGeoFieldsWriter<uindirectPrimitivePatch>
+    uindirectPatchGeoFieldsWriter;
+
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
diff --git a/src/conversion/vtk/output/foamVtkUIndPatchGeoFieldsWriter.H b/src/conversion/vtk/output/foamVtkUIndPatchGeoFieldsWriter.H
index 30b5b5f63e..a4c88a7bcc 100644
--- a/src/conversion/vtk/output/foamVtkUIndPatchGeoFieldsWriter.H
+++ b/src/conversion/vtk/output/foamVtkUIndPatchGeoFieldsWriter.H
@@ -1,67 +1,17 @@
 /*---------------------------------------------------------------------------*\
-  =========                 |
-  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
-   \\    /   O peration     |
-    \\  /    A nd           | www.openfoam.com
-     \\/     M anipulation  |
--------------------------------------------------------------------------------
-    Copyright (C) 2021 OpenCFD Ltd.
--------------------------------------------------------------------------------
-License
-    This file is part of OpenFOAM.
-
-    OpenFOAM is free software: you can redistribute it and/or modify it
-    under the terms of the GNU General Public License as published by
-    the Free Software Foundation, either version 3 of the License, or
-    (at your option) any later version.
-
-    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
-    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
-    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
-    for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
-
-Typedef
-    Foam::vtk::uindirectPatchGeoFieldsWriter
-
 Description
-    Write uindirectPrimitivePatch faces/points
-    as a vtp file or a legacy vtk file
-    with support for geometric fields.
+    Compatibility include
 
-See Also
-    Foam::vtk::GenericPatchWriter
+    foamVtkUIndPatchGeoFieldsWriter.H
+    combined into foamVtkIndPatchGeoFieldsWriter.H
+    (MAY-2022)
 
 \*---------------------------------------------------------------------------*/
 
 #ifndef Foam_vtk_UIndPatchGeoFieldsWriter_H
 #define Foam_vtk_UIndPatchGeoFieldsWriter_H
 
-#include "foamVtkGenericPatchGeoFieldsWriter.H"
-#include "uindirectPrimitivePatch.H"
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-namespace Foam
-{
-namespace vtk
-{
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-typedef
-    GenericPatchGeoFieldsWriter<uindirectPrimitivePatch>
-    uindirectPatchGeoFieldsWriter;
-
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-} // End namespace vtk
-} // End namespace Foam
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+#include "foamVtkIndPatchGeoFieldsWriter.H"
 
 #endif
 
diff --git a/src/dynamicFaMesh/interfaceTrackingFvMesh/freeSurfacePointDisplacement.C b/src/dynamicFaMesh/interfaceTrackingFvMesh/freeSurfacePointDisplacement.C
index 46e1deffda..d8d92e959c 100644
--- a/src/dynamicFaMesh/interfaceTrackingFvMesh/freeSurfacePointDisplacement.C
+++ b/src/dynamicFaMesh/interfaceTrackingFvMesh/freeSurfacePointDisplacement.C
@@ -28,6 +28,7 @@ License
 #include "interfaceTrackingFvMesh.H"
 #include "primitivePatchInterpolation.H"
 #include "emptyFaPatch.H"
+#include "processorFaPatch.H"
 #include "wedgeFaPatch.H"
 #include "wallFvPatch.H"
 #include "coordinateSystem.H"
diff --git a/src/dynamicFaMesh/interfaceTrackingFvMesh/interfaceTrackingFvMesh.C b/src/dynamicFaMesh/interfaceTrackingFvMesh/interfaceTrackingFvMesh.C
index 5e2cb8a3ca..8642f515db 100644
--- a/src/dynamicFaMesh/interfaceTrackingFvMesh/interfaceTrackingFvMesh.C
+++ b/src/dynamicFaMesh/interfaceTrackingFvMesh/interfaceTrackingFvMesh.C
@@ -30,6 +30,7 @@ License
 #include "addToRunTimeSelectionTable.H"
 #include "motionSolver.H"
 #include "volFields.H"
+#include "processorFaPatch.H"
 #include "wedgeFaPatch.H"
 #include "wedgeFaPatchFields.H"
 #include "slipFaPatchFields.H"
@@ -48,7 +49,7 @@ License
 #include "turbulentTransportModel.H"
 #include "demandDrivenData.H"
 #include "unitConversion.H"
-#include "foamVtkUIndPatchWriter.H"
+#include "foamVtkIndPatchWriter.H"
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
diff --git a/src/dynamicMesh/attachDetach/attachDetachPointMatchMap.C b/src/dynamicMesh/attachDetach/attachDetachPointMatchMap.C
index 64f88bac9c..0baf651ead 100644
--- a/src/dynamicMesh/attachDetach/attachDetachPointMatchMap.C
+++ b/src/dynamicMesh/attachDetach/attachDetachPointMatchMap.C
@@ -29,7 +29,7 @@ License
 #include "attachDetach.H"
 #include "polyMesh.H"
 #include "primitiveMesh.H"
-#include "primitiveFacePatch.H"
+#include "primitivePatch.H"
 #include "polyTopoChanger.H"
 
 // * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
diff --git a/src/dynamicMesh/boundaryMesh/boundaryMesh.C b/src/dynamicMesh/boundaryMesh/boundaryMesh.C
index 8dd9e5810a..78640758c7 100644
--- a/src/dynamicMesh/boundaryMesh/boundaryMesh.C
+++ b/src/dynamicMesh/boundaryMesh/boundaryMesh.C
@@ -36,8 +36,8 @@ License
 #include "triSurface.H"
 #include "SortableList.H"
 #include "OFstream.H"
-#include "primitiveFacePatch.H"
-#include "uindirectPrimitivePatch.H"
+#include "primitivePatch.H"
+#include "indirectPrimitivePatch.H"
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
diff --git a/src/dynamicMesh/createShellMesh/createShellMesh.H b/src/dynamicMesh/createShellMesh/createShellMesh.H
index 7a5cd13425..be995f65b6 100644
--- a/src/dynamicMesh/createShellMesh/createShellMesh.H
+++ b/src/dynamicMesh/createShellMesh/createShellMesh.H
@@ -38,12 +38,12 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef createShellMesh_H
-#define createShellMesh_H
+#ifndef Foam_createShellMesh_H
+#define Foam_createShellMesh_H
 
-#include "primitiveFacePatch.H"
 #include "bitSet.H"
 #include "labelPair.H"
+#include "primitivePatch.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
diff --git a/src/dynamicMesh/layerAdditionRemoval/layerAdditionRemoval.H b/src/dynamicMesh/layerAdditionRemoval/layerAdditionRemoval.H
index 373d84ef80..2cb206a7a4 100644
--- a/src/dynamicMesh/layerAdditionRemoval/layerAdditionRemoval.H
+++ b/src/dynamicMesh/layerAdditionRemoval/layerAdditionRemoval.H
@@ -37,11 +37,11 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef layerAdditionRemoval_H
-#define layerAdditionRemoval_H
+#ifndef Foam_layerAdditionRemoval_H
+#define Foam_layerAdditionRemoval_H
 
 #include "polyMeshModifier.H"
-#include "primitiveFacePatch.H"
+#include "primitivePatch.H"
 #include "ZoneIDs.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
diff --git a/src/dynamicMesh/polyMeshAdder/faceCoupleInfo.H b/src/dynamicMesh/polyMeshAdder/faceCoupleInfo.H
index afa78dce6a..e21c5323f4 100644
--- a/src/dynamicMesh/polyMeshAdder/faceCoupleInfo.H
+++ b/src/dynamicMesh/polyMeshAdder/faceCoupleInfo.H
@@ -133,12 +133,12 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef faceCoupleInfo_H
-#define faceCoupleInfo_H
+#ifndef Foam_faceCoupleInfo_H
+#define Foam_faceCoupleInfo_H
 
 #include "pointField.H"
 #include "indirectPrimitivePatch.H"
-#include "primitiveFacePatch.H"
+#include "primitivePatch.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
@@ -147,7 +147,6 @@ namespace Foam
 
 typedef HashTable<labelList, edge, Hash<edge>> edgeLookup;
 
-
 // Forward Declarations
 class face;
 class primitiveMesh;
diff --git a/src/dynamicMesh/polyTopoChange/polyTopoChange/addPatchCellLayer.C b/src/dynamicMesh/polyTopoChange/polyTopoChange/addPatchCellLayer.C
index b0efd6df4b..fa1d8b90dc 100644
--- a/src/dynamicMesh/polyTopoChange/polyTopoChange/addPatchCellLayer.C
+++ b/src/dynamicMesh/polyTopoChange/polyTopoChange/addPatchCellLayer.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2015-2017,2020-2021 OpenCFD Ltd.
+    Copyright (C) 2015-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -1201,30 +1201,30 @@ void Foam::addPatchCellLayer::calcExtrudeInfo
 
             if (otherProci != -1)
             {
-                if (gd[Pstream::myProcNo()].found(otherProci))
+                // Use existing processorPolyPatch to otherProci?
+
+                label procPatchi =
+                    gd.topology().procPatchLookup(otherProci);
+
+                if (procPatchi < 0)
                 {
-                    // There is already a processorPolyPatch to otherProci.
-                    // Use it. Note that we can only index procPatchMap
-                    // if the processor actually is a neighbour processor
-                    // so that is why we first check.
-                    edgePatchID[edgei] = gd.procPatchMap()[otherProci];
-                }
-                else
-                {
-                    // Cannot find a patch to processor. See if already
-                    // marked for addition
-                    if (nbrProcToPatch.found(otherProci))
+                    // No existing processorPolyPatch to otherProci.
+                    // See if already marked for addition
+                    procPatchi = nbrProcToPatch.lookup(otherProci, -1);
+
+                    if (procPatchi < 0)
                     {
-                        edgePatchID[edgei] = nbrProcToPatch[otherProci];
-                    }
-                    else
-                    {
-                        edgePatchID[edgei] = nPatches;
-                        nbrProcToPatch.insert(otherProci, nPatches);
-                        patchToNbrProc.insert(nPatches, otherProci);
-                        nPatches++;
+                        // Add new proc-patch, mark for addition.
+
+                        procPatchi = nPatches;
+                        ++nPatches;
+
+                        nbrProcToPatch.insert(otherProci, procPatchi);
+                        patchToNbrProc.insert(procPatchi, otherProci);
                     }
                 }
+
+                edgePatchID[edgei] = procPatchi;
             }
         }
     }
diff --git a/src/dynamicMesh/polyTopoChange/polyTopoChange/hexRef8/hexRef8Data.C b/src/dynamicMesh/polyTopoChange/polyTopoChange/hexRef8/hexRef8Data.C
index f74ff1be9a..388dcbeda0 100644
--- a/src/dynamicMesh/polyTopoChange/polyTopoChange/hexRef8/hexRef8Data.C
+++ b/src/dynamicMesh/polyTopoChange/polyTopoChange/hexRef8/hexRef8Data.C
@@ -27,7 +27,7 @@ License
 \*---------------------------------------------------------------------------*/
 
 #include "IOobject.H"
-#include "UList.H"
+#include "List.H"
 #include "hexRef8Data.H"
 #include "mapPolyMesh.H"
 #include "mapDistributePolyMesh.H"
diff --git a/src/dynamicMesh/polyTopoChange/polyTopoChange/hexRef8/refinementHistory.C b/src/dynamicMesh/polyTopoChange/polyTopoChange/hexRef8/refinementHistory.C
index f8dc175c9c..93a78cd277 100644
--- a/src/dynamicMesh/polyTopoChange/polyTopoChange/hexRef8/refinementHistory.C
+++ b/src/dynamicMesh/polyTopoChange/polyTopoChange/hexRef8/refinementHistory.C
@@ -1048,8 +1048,8 @@ Foam::autoPtr<Foam::refinementHistory> Foam::refinementHistory::clone
             new refinementHistory
             (
                 io,
-                DynamicList<splitCell8>(0),
-                labelList(0),
+                List<splitCell8>(),
+                labelList(),
                 false
             )
         );
diff --git a/src/dynamicMesh/slidingInterface/enrichedPatch/enrichedPatch.H b/src/dynamicMesh/slidingInterface/enrichedPatch/enrichedPatch.H
index 0ed15b67bd..a67de9d114 100644
--- a/src/dynamicMesh/slidingInterface/enrichedPatch/enrichedPatch.H
+++ b/src/dynamicMesh/slidingInterface/enrichedPatch/enrichedPatch.H
@@ -51,12 +51,12 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef enrichedPatch_H
-#define enrichedPatch_H
+#ifndef Foam_enrichedPatch_H
+#define Foam_enrichedPatch_H
 
-#include "primitiveFacePatch.H"
 #include "Map.H"
 #include "point.H"
+#include "primitivePatch.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
diff --git a/src/dynamicMesh/slidingInterface/slidingInterface.H b/src/dynamicMesh/slidingInterface/slidingInterface.H
index f4ffa5e14e..064a5e49f7 100644
--- a/src/dynamicMesh/slidingInterface/slidingInterface.H
+++ b/src/dynamicMesh/slidingInterface/slidingInterface.H
@@ -52,11 +52,11 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef slidingInterface_H
-#define slidingInterface_H
+#ifndef Foam_slidingInterface_H
+#define Foam_slidingInterface_H
 
 #include "polyMeshModifier.H"
-#include "primitiveFacePatch.H"
+#include "primitivePatch.H"
 #include "polyPatchID.H"
 #include "ZoneIDs.H"
 #include "intersection.H"
diff --git a/src/fileFormats/ensight/file/ensightFile.C b/src/fileFormats/ensight/file/ensightFile.C
index ac616ad652..940416dca2 100644
--- a/src/fileFormats/ensight/file/ensightFile.C
+++ b/src/fileFormats/ensight/file/ensightFile.C
@@ -28,7 +28,7 @@ License
 
 #include "ensightFile.H"
 #include "error.H"
-#include "UList.H"
+#include "List.H"
 #include <cstring>
 #include <sstream>
 
diff --git a/src/fileFormats/ensight/part/faces/ensightFacesAddr.C b/src/fileFormats/ensight/part/faces/ensightFacesAddr.C
index 79273ba508..892eba2b83 100644
--- a/src/fileFormats/ensight/part/faces/ensightFacesAddr.C
+++ b/src/fileFormats/ensight/part/faces/ensightFacesAddr.C
@@ -31,7 +31,7 @@ License
 #include "polyMesh.H"
 #include "globalIndex.H"
 #include "globalMeshData.H"
-#include "uindirectPrimitivePatch.H"
+#include "indirectPrimitivePatch.H"
 
 // * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
 
diff --git a/src/fileFormats/ensight/part/faces/ensightFacesIO.C b/src/fileFormats/ensight/part/faces/ensightFacesIO.C
index 3e9b741d98..b23a5b9afa 100644
--- a/src/fileFormats/ensight/part/faces/ensightFacesIO.C
+++ b/src/fileFormats/ensight/part/faces/ensightFacesIO.C
@@ -31,7 +31,7 @@ License
 #include "polyMesh.H"
 #include "globalIndex.H"
 #include "globalMeshData.H"
-#include "uindirectPrimitivePatch.H"
+#include "indirectPrimitivePatch.H"
 
 // * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
 
diff --git a/src/fileFormats/vtk/format/foamVtkFormatter.H b/src/fileFormats/vtk/format/foamVtkFormatter.H
index da8b33e00b..6814704bd4 100644
--- a/src/fileFormats/vtk/format/foamVtkFormatter.H
+++ b/src/fileFormats/vtk/format/foamVtkFormatter.H
@@ -46,7 +46,7 @@ SourceFiles
 #include "uint64.H"
 #include "direction.H"
 #include "word.H"
-#include "UList.H"
+#include "List.H"
 #include "DynamicList.H"
 #include "foamVtkCore.H"
 #include "foamVtkPTraits.H"
diff --git a/src/finiteArea/faMatrices/faMatrix/faMatrix.C b/src/finiteArea/faMatrices/faMatrix/faMatrix.C
index 2d646e7851..58e7f8cef6 100644
--- a/src/finiteArea/faMatrices/faMatrix/faMatrix.C
+++ b/src/finiteArea/faMatrices/faMatrix/faMatrix.C
@@ -30,7 +30,7 @@ License
 #include "edgeFields.H"
 #include "calculatedFaPatchFields.H"
 #include "zeroGradientFaPatchFields.H"
-#include "UIndirectList.H"
+#include "IndirectList.H"
 #include "UniformList.H"
 #include "demandDrivenData.H"
 
diff --git a/src/finiteArea/faMesh/faGlobalMeshData/faGlobalMeshData.C b/src/finiteArea/faMesh/faGlobalMeshData/faGlobalMeshData.C
index 2df0739f11..0c8e68f8f4 100644
--- a/src/finiteArea/faMesh/faGlobalMeshData/faGlobalMeshData.C
+++ b/src/finiteArea/faMesh/faGlobalMeshData/faGlobalMeshData.C
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2016-2017 Wikki Ltd
+    Copyright (C) 2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -23,8 +24,6 @@ License
     You should have received a copy of the GNU General Public License
     along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
 
-Description
-
 Author
     Hrvoje Jasak
 
@@ -33,16 +32,25 @@ Author
 #include "faGlobalMeshData.H"
 #include "faMesh.H"
 #include "globalMeshData.H"
+#include "processorFaPatch.H"
+#include "processorTopologyNew.H"
 
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
 Foam::faGlobalMeshData::faGlobalMeshData(const faMesh& mesh)
 :
-    faProcessorTopology(mesh.boundary(), UPstream::worldComm),
     mesh_(mesh),
+    processorTopology_
+    (
+        processorTopology::New<processorFaPatch>
+        (
+            mesh.boundary(),
+            UPstream::worldComm
+        )
+    ),
     nGlobalPoints_(-1),
-    sharedPointLabels_(0),
-    sharedPointAddr_(0)
+    sharedPointLabels_(),
+    sharedPointAddr_()
 {
     updateMesh();
 }
@@ -50,13 +58,14 @@ Foam::faGlobalMeshData::faGlobalMeshData(const faMesh& mesh)
 
 // * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
 
+// A non-default destructor since we had incomplete types in the header
 Foam::faGlobalMeshData::~faGlobalMeshData()
 {}
 
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
-const Foam::faMesh& Foam::faGlobalMeshData::mesh() const
+const Foam::faMesh& Foam::faGlobalMeshData::mesh() const noexcept
 {
     return mesh_;
 }
diff --git a/src/finiteArea/faMesh/faGlobalMeshData/faGlobalMeshData.H b/src/finiteArea/faMesh/faGlobalMeshData/faGlobalMeshData.H
index ef4c3e3fed..c494e22f53 100644
--- a/src/finiteArea/faMesh/faGlobalMeshData/faGlobalMeshData.H
+++ b/src/finiteArea/faMesh/faGlobalMeshData/faGlobalMeshData.H
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2016-2017 Wikki Ltd
+    Copyright (C) 2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -35,17 +36,17 @@ Author
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef faGlobalMeshData_H
-#define faGlobalMeshData_H
+#ifndef Foam_faGlobalMeshData_H
+#define Foam_faGlobalMeshData_H
 
-#include "faProcessorTopology.H"
+#include "processorTopology.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 namespace Foam
 {
 
-// Class forward declarations
+// Class Declarations
 class faMesh;
 
 /*---------------------------------------------------------------------------*\
@@ -53,25 +54,28 @@ class faMesh;
 \*---------------------------------------------------------------------------*/
 
 class faGlobalMeshData
-:
-    public faProcessorTopology
 {
-    // Private data
+    // Private Data
 
         //- Reference to mesh
         const faMesh& mesh_;
 
-        // Globally shared point addressing
+        //- The processor/processor topology
+        processorTopology processorTopology_;
 
-            //- Total number of global points
-            label nGlobalPoints_;
 
-            //- Indices of local points that are globally shared
-            labelList sharedPointLabels_;
+    // Globally shared point addressing
+
+        //- Total number of global points
+        label nGlobalPoints_;
+
+        //- Indices of local points that are globally shared
+        labelList sharedPointLabels_;
+
+        //- Indices of globally shared points in the master list
+        //  This list contains all the shared points in the mesh
+        labelList sharedPointAddr_;
 
-            //- Indices of globally shared points in the master list
-            //  This list contains all the shared points in the mesh
-            labelList sharedPointAddr_;
 
     // Private Member Functions
 
@@ -87,8 +91,12 @@ public:
     //- Runtime type information
     ClassName("faGlobalMeshData");
 
-    //- Construct from mesh
-    faGlobalMeshData(const faMesh& mesh);
+
+    // Constructors
+
+        //- Construct from mesh
+        explicit faGlobalMeshData(const faMesh& mesh);
+
 
     //- Destructor
     ~faGlobalMeshData();
@@ -96,34 +104,50 @@ public:
 
     // Member Functions
 
-        // Access
+    // Access
 
-            //- Return mesh reference
-            const faMesh& mesh() const;
+        //- Return mesh reference
+        const faMesh& mesh() const noexcept;
 
-        // Globally shared point addressing
 
-            //- Return number of globally shared points
-            label nGlobalPoints() const
-            {
-                return nGlobalPoints_;
-            }
+    // Processor-Topology
 
-            //- Return indices of local points that are globally shared
-            const labelList& sharedPointLabels() const
-            {
-                return sharedPointLabels_;
-            }
+        //- The processor to processor topology.
+        const processorTopology& topology() const noexcept
+        {
+            return processorTopology_;
+        }
 
-            //- Return addressing into the complete globally shared points
-            //  list
-            const labelList& sharedPointAddr() const
-            {
-                return sharedPointAddr_;
-            }
+        //- Order in which the patches should be initialised/evaluated
+        //- corresponding to the schedule
+        const lduSchedule& patchSchedule() const noexcept
+        {
+            return processorTopology_.patchSchedule();
+        }
 
-            //- Change global mesh data given a topological change.
-            void updateMesh();
+
+    // Globally shared point addressing
+
+        //- Return number of globally shared points
+        label nGlobalPoints() const noexcept
+        {
+            return nGlobalPoints_;
+        }
+
+        //- Return indices of local points that are globally shared
+        const labelList& sharedPointLabels() const noexcept
+        {
+            return sharedPointLabels_;
+        }
+
+        //- Return addressing into the complete globally shared points list
+        const labelList& sharedPointAddr() const noexcept
+        {
+            return sharedPointAddr_;
+        }
+
+        //- Change global mesh data given a topological change.
+        void updateMesh();
 };
 
 
diff --git a/src/finiteArea/faMesh/faGlobalMeshData/faProcessorTopology.H b/src/finiteArea/faMesh/faGlobalMeshData/faProcessorTopology.H
deleted file mode 100644
index 607ff448f5..0000000000
--- a/src/finiteArea/faMesh/faGlobalMeshData/faProcessorTopology.H
+++ /dev/null
@@ -1,60 +0,0 @@
-/*---------------------------------------------------------------------------*\
-  =========                 |
-  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
-   \\    /   O peration     |
-    \\  /    A nd           | www.openfoam.com
-     \\/     M anipulation  |
--------------------------------------------------------------------------------
-    Copyright (C) 2016-2017 Wikki Ltd
--------------------------------------------------------------------------------
-License
-    This file is part of OpenFOAM.
-
-    OpenFOAM is free software: you can redistribute it and/or modify it
-    under the terms of the GNU General Public License as published by
-    the Free Software Foundation, either version 3 of the License, or
-    (at your option) any later version.
-
-    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
-    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
-    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
-    for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
-
-Typedef
-    Foam::faProcessorTopology
-
-Description
-
-Author
-    Zeljko Tukovic, FMENA
-    Hrvoje Jasak, Wikki Ltd.
-
-\*---------------------------------------------------------------------------*/
-
-#ifndef Foam_faProcessorTopology_H
-#define Foam_faProcessorTopology_H
-
-#include "ProcessorTopology.H"
-#include "processorFaPatch.H"
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-namespace Foam
-{
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-typedef ProcessorTopology<faPatchList, processorFaPatch> faProcessorTopology;
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-} // End namespace Foam
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-#endif
-
-// ************************************************************************* //
diff --git a/src/finiteArea/faMesh/faMesh.H b/src/finiteArea/faMesh/faMesh.H
index 3cdcc6811f..c6de146f0f 100644
--- a/src/finiteArea/faMesh/faMesh.H
+++ b/src/finiteArea/faMesh/faMesh.H
@@ -66,7 +66,7 @@ Author
 #include "DimensionedField.H"
 #include "areaFieldsFwd.H"
 #include "edgeFieldsFwd.H"
-#include "uindirectPrimitivePatch.H"
+#include "indirectPrimitivePatch.H"
 #include "edgeInterpolation.H"
 #include "labelIOList.H"
 #include "FieldFields.H"
diff --git a/src/finiteArea/faMesh/faMeshBoundaryHaloTemplates.C b/src/finiteArea/faMesh/faMeshBoundaryHaloTemplates.C
index 69f2214b04..fd167f2b6c 100644
--- a/src/finiteArea/faMesh/faMeshBoundaryHaloTemplates.C
+++ b/src/finiteArea/faMesh/faMeshBoundaryHaloTemplates.C
@@ -26,7 +26,7 @@ License
 \*---------------------------------------------------------------------------*/
 
 #include "faMeshBoundaryHalo.H"
-#include "UIndirectList.H"
+#include "IndirectList.H"
 #include "Pstream.H"
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
diff --git a/src/finiteArea/faMesh/faMeshDemandDrivenData.C b/src/finiteArea/faMesh/faMeshDemandDrivenData.C
index cdab918b40..c6af8c0499 100644
--- a/src/finiteArea/faMesh/faMeshDemandDrivenData.C
+++ b/src/finiteArea/faMesh/faMeshDemandDrivenData.C
@@ -30,7 +30,6 @@ License
 #include "faMeshLduAddressing.H"
 #include "areaFields.H"
 #include "edgeFields.H"
-#include "primitiveFacePatch.H"
 #include "fac.H"
 #include "processorFaPatch.H"
 #include "wedgeFaPatch.H"
diff --git a/src/finiteArea/faMesh/faMeshTopology.C b/src/finiteArea/faMesh/faMeshTopology.C
index 938dbe9dbd..752e6b286c 100644
--- a/src/finiteArea/faMesh/faMeshTopology.C
+++ b/src/finiteArea/faMesh/faMeshTopology.C
@@ -32,7 +32,6 @@ License
 #include "edgeHashes.H"
 #include "foamVtkLineWriter.H"
 #include "foamVtkIndPatchWriter.H"
-#include "foamVtkUIndPatchWriter.H"
 
 // * * * * * * * * * * * * * * * Local Functions * * * * * * * * * * * * * * //
 
diff --git a/src/finiteArea/faMesh/faPatches/constraint/processor/processorFaPatch.C b/src/finiteArea/faMesh/faPatches/constraint/processor/processorFaPatch.C
index 15f2eb9933..2b3a1a5df9 100644
--- a/src/finiteArea/faMesh/faPatches/constraint/processor/processorFaPatch.C
+++ b/src/finiteArea/faMesh/faPatches/constraint/processor/processorFaPatch.C
@@ -27,6 +27,7 @@ License
 \*---------------------------------------------------------------------------*/
 
 #include "processorFaPatch.H"
+#include "processorPolyPatch.H"  // For newName()
 #include "addToRunTimeSelectionTable.H"
 #include "transformField.H"
 #include "faBoundaryMesh.H"
diff --git a/src/finiteVolume/fields/fvPatchFields/derived/mappedFixedInternalValue/mappedFixedInternalValueFvPatchField.C b/src/finiteVolume/fields/fvPatchFields/derived/mappedFixedInternalValue/mappedFixedInternalValueFvPatchField.C
index c5a44b05a8..89d6ec1ee4 100644
--- a/src/finiteVolume/fields/fvPatchFields/derived/mappedFixedInternalValue/mappedFixedInternalValueFvPatchField.C
+++ b/src/finiteVolume/fields/fvPatchFields/derived/mappedFixedInternalValue/mappedFixedInternalValueFvPatchField.C
@@ -26,7 +26,7 @@ License
 \*---------------------------------------------------------------------------*/
 
 #include "mappedFixedInternalValueFvPatchField.H"
-#include "UIndirectList.H"
+#include "IndirectList.H"
 
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
diff --git a/src/finiteVolume/fields/fvPatchFields/derived/mappedFixedPushedInternalValue/mappedFixedPushedInternalValueFvPatchField.C b/src/finiteVolume/fields/fvPatchFields/derived/mappedFixedPushedInternalValue/mappedFixedPushedInternalValueFvPatchField.C
index edb3b3ce84..5b6a841728 100644
--- a/src/finiteVolume/fields/fvPatchFields/derived/mappedFixedPushedInternalValue/mappedFixedPushedInternalValueFvPatchField.C
+++ b/src/finiteVolume/fields/fvPatchFields/derived/mappedFixedPushedInternalValue/mappedFixedPushedInternalValueFvPatchField.C
@@ -26,7 +26,7 @@ License
 \*---------------------------------------------------------------------------*/
 
 #include "mappedFixedPushedInternalValueFvPatchField.H"
-#include "UIndirectList.H"
+#include "IndirectList.H"
 
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
diff --git a/src/finiteVolume/fvMatrices/fvMatrix/fvMatrix.C b/src/finiteVolume/fvMatrices/fvMatrix/fvMatrix.C
index 01463b85ee..b59076769a 100644
--- a/src/finiteVolume/fvMatrices/fvMatrix/fvMatrix.C
+++ b/src/finiteVolume/fvMatrices/fvMatrix/fvMatrix.C
@@ -31,7 +31,7 @@ License
 #include "calculatedFvPatchFields.H"
 #include "extrapolatedCalculatedFvPatchFields.H"
 #include "coupledFvPatchFields.H"
-#include "UIndirectList.H"
+#include "IndirectList.H"
 #include "UniformList.H"
 #include "demandDrivenData.H"
 
diff --git a/src/finiteVolume/fvMesh/fvMeshSubset/fvMeshSubset.C b/src/finiteVolume/fvMesh/fvMeshSubset/fvMeshSubset.C
index 2466022c82..fbac703933 100644
--- a/src/finiteVolume/fvMesh/fvMeshSubset/fvMeshSubset.C
+++ b/src/finiteVolume/fvMesh/fvMeshSubset/fvMeshSubset.C
@@ -31,6 +31,7 @@ License
 #include "Pstream.H"
 #include "cyclicPolyPatch.H"
 #include "emptyPolyPatch.H"
+#include "processorPolyPatch.H"
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
diff --git a/src/finiteVolume/fvMesh/singleCellFvMesh/singleCellFvMesh.C b/src/finiteVolume/fvMesh/singleCellFvMesh/singleCellFvMesh.C
index 740968ea3e..f3b975a44a 100644
--- a/src/finiteVolume/fvMesh/singleCellFvMesh/singleCellFvMesh.C
+++ b/src/finiteVolume/fvMesh/singleCellFvMesh/singleCellFvMesh.C
@@ -28,7 +28,7 @@ License
 
 #include "singleCellFvMesh.H"
 #include "syncTools.H"
-#include "uindirectPrimitivePatch.H"
+#include "indirectPrimitivePatch.H"
 
 // * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
 
diff --git a/src/functionObjects/field/fieldExtents/fieldExtents.C b/src/functionObjects/field/fieldExtents/fieldExtents.C
index f974f3d854..db42a4ac55 100644
--- a/src/functionObjects/field/fieldExtents/fieldExtents.C
+++ b/src/functionObjects/field/fieldExtents/fieldExtents.C
@@ -26,6 +26,7 @@ License
 \*---------------------------------------------------------------------------*/
 
 #include "fieldExtents.H"
+#include "processorPolyPatch.H"
 #include "addToRunTimeSelectionTable.H"
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
diff --git a/src/functionObjects/utilities/areaWrite/areaWrite.C b/src/functionObjects/utilities/areaWrite/areaWrite.C
index d0bc87ca40..d352615f70 100644
--- a/src/functionObjects/utilities/areaWrite/areaWrite.C
+++ b/src/functionObjects/utilities/areaWrite/areaWrite.C
@@ -34,7 +34,7 @@ License
 #include "HashOps.H"
 #include "ListOps.H"
 #include "Time.H"
-#include "UIndirectList.H"
+#include "IndirectList.H"
 #include "addToRunTimeSelectionTable.H"
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
diff --git a/src/functionObjects/utilities/vtkWrite/vtkWriteUpdate.C b/src/functionObjects/utilities/vtkWrite/vtkWriteUpdate.C
index bca349bbfc..0953b39ccd 100644
--- a/src/functionObjects/utilities/vtkWrite/vtkWriteUpdate.C
+++ b/src/functionObjects/utilities/vtkWrite/vtkWriteUpdate.C
@@ -28,6 +28,7 @@ License
 #include "vtkWrite.H"
 #include "cellBitSet.H"
 #include "topoSetCellSource.H"
+#include "processorPolyPatch.H"
 
 // * * * * * * * * * * * * * * Local Data Members  * * * * * * * * * * * * * //
 
diff --git a/src/fvMotionSolver/fvMotionSolvers/displacement/surfaceAlignedSBRStress/surfaceAlignedSBRStressFvMotionSolver.C b/src/fvMotionSolver/fvMotionSolvers/displacement/surfaceAlignedSBRStress/surfaceAlignedSBRStressFvMotionSolver.C
index a888fd225d..954cbd9677 100644
--- a/src/fvMotionSolver/fvMotionSolvers/displacement/surfaceAlignedSBRStress/surfaceAlignedSBRStressFvMotionSolver.C
+++ b/src/fvMotionSolver/fvMotionSolvers/displacement/surfaceAlignedSBRStress/surfaceAlignedSBRStressFvMotionSolver.C
@@ -29,6 +29,7 @@ License
 #include "surfaceAlignedSBRStressFvMotionSolver.H"
 #include "addToRunTimeSelectionTable.H"
 #include "pointIndexHit.H"
+#include "processorPolyPatch.H"
 #include "fvmLaplacian.H"
 #include "fvcDiv.H"
 #include "surfaceInterpolate.H"
diff --git a/src/lagrangian/basic/Cloud/Cloud.C b/src/lagrangian/basic/Cloud/Cloud.C
index 5b7aa9a9f7..a6061e62a7 100644
--- a/src/lagrangian/basic/Cloud/Cloud.C
+++ b/src/lagrangian/basic/Cloud/Cloud.C
@@ -161,7 +161,8 @@ void Foam::Cloud<ParticleType>::move
     const labelList& procPatchNeighbours = pData.processorPatchNeighbours();
 
     // Which processors this processor is connected to
-    const labelList& neighbourProcs = pData[Pstream::myProcNo()];
+    const labelList& neighbourProcs =
+        pData.topology().procNeighbours()[Pstream::myProcNo()];
 
     // Initialise the stepFraction moved for the particles
     for (ParticleType& p : *this)
diff --git a/src/mesh/snappyHexMesh/meshRefinement/meshRefinement.H b/src/mesh/snappyHexMesh/meshRefinement/meshRefinement.H
index cd9ef23c60..872e0bb8c8 100644
--- a/src/mesh/snappyHexMesh/meshRefinement/meshRefinement.H
+++ b/src/mesh/snappyHexMesh/meshRefinement/meshRefinement.H
@@ -44,15 +44,14 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef meshRefinement_H
-#define meshRefinement_H
+#ifndef Foam_meshRefinement_H
+#define Foam_meshRefinement_H
 
 #include "hexRef8.H"
 #include "mapPolyMesh.H"
 #include "autoPtr.H"
 #include "labelPairHashes.H"
 #include "indirectPrimitivePatch.H"
-#include "uindirectPrimitivePatch.H"
 #include "pointFieldsFwd.H"
 #include "Tuple2.H"
 #include "pointIndexHit.H"
diff --git a/src/mesh/snappyHexMesh/meshRefinement/meshRefinementBlock.C b/src/mesh/snappyHexMesh/meshRefinement/meshRefinementBlock.C
index f17d933a83..7526f5d52d 100644
--- a/src/mesh/snappyHexMesh/meshRefinement/meshRefinementBlock.C
+++ b/src/mesh/snappyHexMesh/meshRefinement/meshRefinementBlock.C
@@ -49,7 +49,7 @@ License
 
 #include "holeToFace.H"
 #include "refinementParameters.H"
-#include "uindirectPrimitivePatch.H"
+#include "indirectPrimitivePatch.H"
 #include "OBJstream.H"
 #include "PatchTools.H"
 
diff --git a/src/meshTools/meshStructure/meshStructure.H b/src/meshTools/meshStructure/meshStructure.H
index 65aa43eaae..a378a322cd 100644
--- a/src/meshTools/meshStructure/meshStructure.H
+++ b/src/meshTools/meshStructure/meshStructure.H
@@ -39,11 +39,11 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef meshStructure_H
-#define meshStructure_H
+#ifndef Foam_meshStructure_H
+#define Foam_meshStructure_H
 
 #include "labelList.H"
-#include "uindirectPrimitivePatch.H"
+#include "indirectPrimitivePatch.H"
 #include "className.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
@@ -51,7 +51,7 @@ SourceFiles
 namespace Foam
 {
 
-// Forward declaration of classes
+// Forward Declaration
 class polyMesh;
 class globalIndex;
 
diff --git a/src/meshTools/output/vtk/patch/foamVtkIndPatchWriter.H b/src/meshTools/output/vtk/patch/foamVtkIndPatchWriter.H
index f3ec980047..feced743dd 100644
--- a/src/meshTools/output/vtk/patch/foamVtkIndPatchWriter.H
+++ b/src/meshTools/output/vtk/patch/foamVtkIndPatchWriter.H
@@ -30,6 +30,13 @@ Description
     Write indirectPrimitivePatch faces/points (optionally with fields)
     as a vtp file or a legacy vtk file.
 
+Typedef
+    Foam::vtk::uindirectPatchWriter
+
+Description
+    Write uindirectPrimitivePatch faces/points (optionally with fields)
+    as a vtp file or a legacy vtk file.
+
 See Also
     Foam::vtk::GenericPatchWriter
 
@@ -54,6 +61,10 @@ typedef
     GenericPatchWriter<indirectPrimitivePatch>
     indirectPatchWriter;
 
+typedef
+    GenericPatchWriter<uindirectPrimitivePatch>
+    uindirectPatchWriter;
+
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
diff --git a/src/meshTools/output/vtk/patch/foamVtkUIndPatchWriter.H b/src/meshTools/output/vtk/patch/foamVtkUIndPatchWriter.H
index dad72020b0..3e9a91483e 100644
--- a/src/meshTools/output/vtk/patch/foamVtkUIndPatchWriter.H
+++ b/src/meshTools/output/vtk/patch/foamVtkUIndPatchWriter.H
@@ -1,66 +1,15 @@
 /*---------------------------------------------------------------------------*\
-  =========                 |
-  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
-   \\    /   O peration     |
-    \\  /    A nd           | www.openfoam.com
-     \\/     M anipulation  |
--------------------------------------------------------------------------------
-    Copyright (C) 2021 OpenCFD Ltd.
--------------------------------------------------------------------------------
-License
-    This file is part of OpenFOAM.
-
-    OpenFOAM is free software: you can redistribute it and/or modify it
-    under the terms of the GNU General Public License as published by
-    the Free Software Foundation, either version 3 of the License, or
-    (at your option) any later version.
-
-    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
-    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
-    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
-    for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
-
-Typedef
-    Foam::vtk::uindirectPatchWriter
-
 Description
-    Write uindirectPrimitivePatch faces/points (optionally with fields)
-    as a vtp file or a legacy vtk file.
+    Compatibility include
 
-See Also
-    Foam::vtk::GenericPatchWriter
+    foamVtkUIndPatchWriter.H combined into foamVtkIndPatchWriter.H (MAY-2022)
 
 \*---------------------------------------------------------------------------*/
 
 #ifndef Foam_vtk_UIndPatchWriter_H
 #define Foam_vtk_UIndPatchWriter_H
 
-#include "foamVtkGenericPatchWriter.H"
-#include "uindirectPrimitivePatch.H"
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-namespace Foam
-{
-namespace vtk
-{
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-typedef
-    GenericPatchWriter<uindirectPrimitivePatch>
-    uindirectPatchWriter;
-
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-} // End namespace vtk
-} // End namespace Foam
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+#include "foamVtkIndPatchWriter.H"
 
 #endif
 
diff --git a/src/meshTools/polyTopoChange/polyTopoChange.C b/src/meshTools/polyTopoChange/polyTopoChange.C
index c641cce340..58dca2b07c 100644
--- a/src/meshTools/polyTopoChange/polyTopoChange.C
+++ b/src/meshTools/polyTopoChange/polyTopoChange.C
@@ -41,7 +41,6 @@ License
 #include "CompactListList.H"
 #include "objectMap.H"
 #include "processorPolyPatch.H"
-#include "ListOps.H"  // sortedOrder
 #include "mapPolyMesh.H"
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
diff --git a/src/meshTools/topoSet/faceZoneSources/planeToFaceZone/planeToFaceZone.C b/src/meshTools/topoSet/faceZoneSources/planeToFaceZone/planeToFaceZone.C
index dfa9df9afa..45fd131a9d 100644
--- a/src/meshTools/topoSet/faceZoneSources/planeToFaceZone/planeToFaceZone.C
+++ b/src/meshTools/topoSet/faceZoneSources/planeToFaceZone/planeToFaceZone.C
@@ -29,7 +29,7 @@ License
 #include "planeToFaceZone.H"
 #include "polyMesh.H"
 #include "faceZoneSet.H"
-#include "uindirectPrimitivePatch.H"
+#include "indirectPrimitivePatch.H"
 #include "PatchTools.H"
 #include "syncTools.H"
 #include "addToRunTimeSelectionTable.H"
diff --git a/src/overset/cellCellStencil/trackingInverseDistance/voxelMeshSearch.C b/src/overset/cellCellStencil/trackingInverseDistance/voxelMeshSearch.C
index e775a18e6f..cb2f945587 100644
--- a/src/overset/cellCellStencil/trackingInverseDistance/voxelMeshSearch.C
+++ b/src/overset/cellCellStencil/trackingInverseDistance/voxelMeshSearch.C
@@ -27,11 +27,11 @@ License
 
 #include "voxelMeshSearch.H"
 #include "polyMesh.H"
-#include "processorPolyPatch.H"
 #include "IOobject.H"
 #include "fvMesh.H"
 #include "block.H"
 #include "emptyPolyPatch.H"
+#include "processorPolyPatch.H"
 #include "fvMeshTools.H"
 
 /* * * * * * * * * * * * * * * Static Member Data  * * * * * * * * * * * * * */
diff --git a/src/sampling/meshToMesh/meshToMesh.C b/src/sampling/meshToMesh/meshToMesh.C
index b5404474d5..7fbdda2cc4 100644
--- a/src/sampling/meshToMesh/meshToMesh.C
+++ b/src/sampling/meshToMesh/meshToMesh.C
@@ -31,6 +31,7 @@ License
 #include "globalIndex.H"
 #include "meshToMeshMethod.H"
 #include "nearestFaceAMI.H"
+#include "processorPolyPatch.H"
 #include "faceAreaWeightAMI.H"
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
diff --git a/src/sampling/sampledSet/sampledSets/sampledSets.C b/src/sampling/sampledSet/sampledSets/sampledSets.C
index e62a5145bb..34900be083 100644
--- a/src/sampling/sampledSet/sampledSets/sampledSets.C
+++ b/src/sampling/sampledSet/sampledSets/sampledSets.C
@@ -34,7 +34,7 @@ License
 #include "mapPolyMesh.H"
 #include "IOmanip.H"
 #include "IOobjectList.H"
-#include "UIndirectList.H"
+#include "IndirectList.H"
 #include "ListOps.H"
 #include "addToRunTimeSelectionTable.H"
 
diff --git a/src/sampling/sampledSet/shortestPath/shortestPathSet.C b/src/sampling/sampledSet/shortestPath/shortestPathSet.C
index 69096f591b..5e2578acdc 100644
--- a/src/sampling/sampledSet/shortestPath/shortestPathSet.C
+++ b/src/sampling/sampledSet/shortestPath/shortestPathSet.C
@@ -37,7 +37,7 @@ License
 #include "OBJstream.H"
 #include "PatchTools.H"
 #include "foamVtkSurfaceWriter.H"
-#include "uindirectPrimitivePatch.H"
+#include "indirectPrimitivePatch.H"
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
diff --git a/src/sampling/sampledSurface/sampledFaceZone/sampledFaceZone.C b/src/sampling/sampledSurface/sampledFaceZone/sampledFaceZone.C
index 19e5a6914c..9f5c6b167c 100644
--- a/src/sampling/sampledSurface/sampledFaceZone/sampledFaceZone.C
+++ b/src/sampling/sampledSurface/sampledFaceZone/sampledFaceZone.C
@@ -29,10 +29,11 @@ License
 #include "dictionary.H"
 #include "polyMesh.H"
 #include "polyPatch.H"
+#include "processorPolyPatch.H"
 #include "volFields.H"
 #include "surfaceFields.H"
 #include "volPointInterpolation.H"
-#include "uindirectPrimitivePatch.H"
+#include "indirectPrimitivePatch.H"
 
 #include "addToRunTimeSelectionTable.H"
 
diff --git a/src/sampling/sampledSurface/sampledPatch/sampledPatch.C b/src/sampling/sampledSurface/sampledPatch/sampledPatch.C
index 5a175ce469..e684be639e 100644
--- a/src/sampling/sampledSurface/sampledPatch/sampledPatch.C
+++ b/src/sampling/sampledSurface/sampledPatch/sampledPatch.C
@@ -32,7 +32,7 @@ License
 #include "polyPatch.H"
 #include "volFields.H"
 #include "surfaceFields.H"
-#include "uindirectPrimitivePatch.H"
+#include "indirectPrimitivePatch.H"
 
 #include "addToRunTimeSelectionTable.H"
 
diff --git a/src/sampling/sampledSurface/sampledSurfaces/sampledSurfaces.C b/src/sampling/sampledSurface/sampledSurfaces/sampledSurfaces.C
index 98f115ec28..aaa102c9bb 100644
--- a/src/sampling/sampledSurface/sampledSurfaces/sampledSurfaces.C
+++ b/src/sampling/sampledSurface/sampledSurfaces/sampledSurfaces.C
@@ -35,7 +35,7 @@ License
 #include "HashOps.H"
 #include "ListOps.H"
 #include "Time.H"
-#include "UIndirectList.H"
+#include "IndirectList.H"
 #include "addToRunTimeSelectionTable.H"
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
diff --git a/src/sampling/surface/isoSurface/isoSurfaceTopo.C b/src/sampling/surface/isoSurface/isoSurfaceTopo.C
index b1b8aabba6..92c15e1fc5 100644
--- a/src/sampling/surface/isoSurface/isoSurfaceTopo.C
+++ b/src/sampling/surface/isoSurface/isoSurfaceTopo.C
@@ -34,7 +34,7 @@ License
 #include "tetPointRef.H"
 #include "DynamicField.H"
 #include "syncTools.H"
-#include "uindirectPrimitivePatch.H"
+#include "indirectPrimitivePatch.H"
 #include "polyMeshTetDecomposition.H"
 #include "foamVtkInternalMeshWriter.H"
 #include "foamVtkLineWriter.H"