diff --git a/applications/test/List/Test-List.C b/applications/test/List/Test-List.C
index e676a859a4..03e77dcfef 100644
--- a/applications/test/List/Test-List.C
+++ b/applications/test/List/Test-List.C
@@ -81,7 +81,7 @@ namespace ListPolicy
 {
 
 // Override on a per-type basis
-template<> struct short_length<short> : std::integral_constant<short,20> {};
+template<> struct short_length<short> : std::integral_constant<int,20> {};
 
 } // End namespace ListPolicy
 } // End namespace Detail
diff --git a/applications/test/minMax2/Test-minMax2.C b/applications/test/minMax2/Test-minMax2.C
index 136681d75c..ec02d21d3d 100644
--- a/applications/test/minMax2/Test-minMax2.C
+++ b/applications/test/minMax2/Test-minMax2.C
@@ -146,7 +146,7 @@ int main(int argc, char *argv[])
         Random rnd(4567);
         for (scalar& val : someField)
         {
-            val = rnd.position(-0.2, 1.2);
+            val = rnd.position(scalar(-0.2), scalar(1.2));
         }
 
         Info<< nl
@@ -171,6 +171,7 @@ int main(int argc, char *argv[])
             // nope << " : " << clamp(val, zero_one{})
             // nope << " : " << clamp(val, scalarMinMax(zero_one{}))
             << " : " << clamp(val, 0, 1)
+            << " : " << clamp(val, zero_one{})
             << nl;
     }
 
diff --git a/applications/test/sizeof/Test-sizeof.C b/applications/test/sizeof/Test-sizeof.C
index a5bd8ce9a7..13f0aac07a 100644
--- a/applications/test/sizeof/Test-sizeof.C
+++ b/applications/test/sizeof/Test-sizeof.C
@@ -33,7 +33,7 @@ Description
 #include "Switch.H"
 #include "string.H"
 #include "dictionary.H"
-#include "nil.H"
+#include "zero.H"
 #include "IOstreams.H"
 #include "PstreamBuffers.H"
 #include "argList.H"
@@ -82,8 +82,8 @@ int main(int argc, char *argv[])
     }
 
     {
-        nil x;
-        cout<<"nil:" << sizeof(x) << nl;
+        zero x;
+        cout<<"zero:" << sizeof(x) << nl;
     }
     #if 0
     {
diff --git a/applications/utilities/mesh/advanced/selectCells/edgeStats.H b/applications/utilities/mesh/advanced/selectCells/edgeStats.H
index 79e70feba3..d197fdcb30 100644
--- a/applications/utilities/mesh/advanced/selectCells/edgeStats.H
+++ b/applications/utilities/mesh/advanced/selectCells/edgeStats.H
@@ -34,8 +34,8 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef edgeStats_H
-#define edgeStats_H
+#ifndef Foam_edgeStats_H
+#define Foam_edgeStats_H
 
 #include "direction.H"
 #include "scalar.H"
@@ -45,9 +45,8 @@ SourceFiles
 namespace Foam
 {
 
-// Forward declaration of classes
+// Forward Declarations
 class polyMesh;
-class Ostream;
 class twoDPointCorrector;
 
 /*---------------------------------------------------------------------------*\
diff --git a/applications/utilities/preProcessing/PDR/pdrFields/obstacles/PDRobstacleTypes.C b/applications/utilities/preProcessing/PDR/pdrFields/obstacles/PDRobstacleTypes.C
index 31c559d86f..04e798cf0c 100644
--- a/applications/utilities/preProcessing/PDR/pdrFields/obstacles/PDRobstacleTypes.C
+++ b/applications/utilities/preProcessing/PDR/pdrFields/obstacles/PDRobstacleTypes.C
@@ -62,7 +62,7 @@ namespace Foam
 // Volume porosity -> blockage
 inline scalar getPorosity(const dictionary& dict)
 {
-    return 1 - clamp(dict.getOrDefault<scalar>("porosity", 0), 0, 1);
+    return 1 - clamp(dict.getOrDefault<scalar>("porosity", 0), zero_one{});
 }
 
 // Direction porosities -> blockage
@@ -74,7 +74,7 @@ inline vector getPorosities(const dictionary& dict)
     {
         for (scalar& val : blockage)
         {
-            val = 1 - clamp(val, 0, 1);
+            val = 1 - clamp(val, zero_one{});
         }
     }
 
diff --git a/applications/utilities/preProcessing/setAlphaField/setAlphaField.C b/applications/utilities/preProcessing/setAlphaField/setAlphaField.C
index 1db1a547f4..78f9b77e55 100644
--- a/applications/utilities/preProcessing/setAlphaField/setAlphaField.C
+++ b/applications/utilities/preProcessing/setAlphaField/setAlphaField.C
@@ -108,7 +108,7 @@ void setAlpha
     {
         cutCell.calcSubCell(cellI, 0.0);
 
-        alpha1[cellI] = clamp(cutCell.VolumeOfFluid(), 0, 1);
+        alpha1[cellI] = clamp(cutCell.VolumeOfFluid(), zero_one{});
 
         if (writeOBJ && (mag(cutCell.faceArea()) >= 1e-14))
         {
diff --git a/src/OSspecific/MSwindows/cpuInfo/cpuInfo.H b/src/OSspecific/MSwindows/cpuInfo/cpuInfo.H
index 5b175074cb..7da2ac5bc6 100644
--- a/src/OSspecific/MSwindows/cpuInfo/cpuInfo.H
+++ b/src/OSspecific/MSwindows/cpuInfo/cpuInfo.H
@@ -50,7 +50,7 @@ SourceFiles
 namespace Foam
 {
 
-// Forward declarations
+// Forward Declarations
 class Ostream;
 
 /*---------------------------------------------------------------------------*\
diff --git a/src/OSspecific/POSIX/cpuInfo/cpuInfo.H b/src/OSspecific/POSIX/cpuInfo/cpuInfo.H
index f9d5c5646b..37cac03d92 100644
--- a/src/OSspecific/POSIX/cpuInfo/cpuInfo.H
+++ b/src/OSspecific/POSIX/cpuInfo/cpuInfo.H
@@ -50,7 +50,7 @@ SourceFiles
 namespace Foam
 {
 
-// Forward declarations
+// Forward Declarations
 class Ostream;
 
 /*---------------------------------------------------------------------------*\
diff --git a/src/OpenFOAM/Make/files b/src/OpenFOAM/Make/files
index b0404996bc..7753533552 100644
--- a/src/OpenFOAM/Make/files
+++ b/src/OpenFOAM/Make/files
@@ -42,22 +42,21 @@ $(chars)/lists/charUList.C
 primitives/direction/directionIO.C
 
 ints = primitives/ints
+$(ints)/uint/uintIO.C
 $(ints)/uint8/uint8.C
-$(ints)/uint8/uint8IO.C
 $(ints)/uint16/uint16.C
 $(ints)/uint32/uint32.C
 $(ints)/uint32/uint32IO.C
 $(ints)/uint64/uint64.C
 $(ints)/uint64/uint64IO.C
-$(ints)/uint/uintIO.C
+$(ints)/uLabel/uLabel.C
+$(ints)/int/intIO.C
 $(ints)/int16/int16.C
 $(ints)/int32/int32.C
 $(ints)/int32/int32IO.C
 $(ints)/int64/int64.C
 $(ints)/int64/int64IO.C
-$(ints)/int/intIO.C
 $(ints)/label/label.C
-$(ints)/uLabel/uLabel.C
 $(ints)/lists/labelList.C
 $(ints)/lists/labelIOList.C
 $(ints)/lists/labelListIOList.C
diff --git a/src/OpenFOAM/algorithms/dynamicIndexedOctree/dynamicIndexedOctree.H b/src/OpenFOAM/algorithms/dynamicIndexedOctree/dynamicIndexedOctree.H
index 6a93fc4ba6..d1b9aaf3ca 100644
--- a/src/OpenFOAM/algorithms/dynamicIndexedOctree/dynamicIndexedOctree.H
+++ b/src/OpenFOAM/algorithms/dynamicIndexedOctree/dynamicIndexedOctree.H
@@ -48,7 +48,6 @@ namespace Foam
 {
 
 // Forward Declarations
-class Istream;
 template<class Type> class dynamicIndexedOctree;
 template<class Type>
 Ostream& operator<<(Ostream&, const dynamicIndexedOctree<Type>&);
diff --git a/src/OpenFOAM/algorithms/indexedOctree/indexedOctree.H b/src/OpenFOAM/algorithms/indexedOctree/indexedOctree.H
index 3b9878365c..c9c7887e92 100644
--- a/src/OpenFOAM/algorithms/indexedOctree/indexedOctree.H
+++ b/src/OpenFOAM/algorithms/indexedOctree/indexedOctree.H
@@ -53,7 +53,6 @@ namespace Foam
 {
 
 // Forward Declarations
-class Istream;
 template<class Type> class indexedOctree;
 template<class Type> Ostream& operator<<(Ostream&, const indexedOctree<Type>&);
 
diff --git a/src/OpenFOAM/containers/LinkedLists/accessTypes/ILList/ILList.H b/src/OpenFOAM/containers/LinkedLists/accessTypes/ILList/ILList.H
index 038cfb7383..984c3c5400 100644
--- a/src/OpenFOAM/containers/LinkedLists/accessTypes/ILList/ILList.H
+++ b/src/OpenFOAM/containers/LinkedLists/accessTypes/ILList/ILList.H
@@ -47,9 +47,6 @@ namespace Foam
 {
 
 // Forward Declarations
-
-class Istream;
-class Ostream;
 template<class LListBase, class T> class ILList;
 
 template<class LListBase, class T> Istream& operator>>
diff --git a/src/OpenFOAM/containers/LinkedLists/accessTypes/LList/LList.H b/src/OpenFOAM/containers/LinkedLists/accessTypes/LList/LList.H
index c99dc344cd..9e7e39311c 100644
--- a/src/OpenFOAM/containers/LinkedLists/accessTypes/LList/LList.H
+++ b/src/OpenFOAM/containers/LinkedLists/accessTypes/LList/LList.H
@@ -48,10 +48,6 @@ namespace Foam
 {
 
 // Forward Declarations
-
-class Istream;
-class Ostream;
-
 template<class LListBase, class T> class LList;
 
 template<class LListBase, class T>
diff --git a/src/OpenFOAM/containers/LinkedLists/accessTypes/UILList/UILList.H b/src/OpenFOAM/containers/LinkedLists/accessTypes/UILList/UILList.H
index 7c3448af24..c97c523968 100644
--- a/src/OpenFOAM/containers/LinkedLists/accessTypes/UILList/UILList.H
+++ b/src/OpenFOAM/containers/LinkedLists/accessTypes/UILList/UILList.H
@@ -49,8 +49,6 @@ namespace Foam
 {
 
 // Forward Declarations
-class Ostream;
-
 template<class LListBase, class T> class UILList;
 
 template<class LListBase, class T>
diff --git a/src/OpenFOAM/containers/Lists/List/UList.H b/src/OpenFOAM/containers/Lists/List/UList.H
index 2c6339e1c9..01d5d1b562 100644
--- a/src/OpenFOAM/containers/Lists/List/UList.H
+++ b/src/OpenFOAM/containers/Lists/List/UList.H
@@ -57,7 +57,6 @@ SourceFiles
 #include "ListPolicy.H"
 
 #include <iterator>
-#include <type_traits>
 #include <vector>  // i.e, std::vector
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
@@ -66,8 +65,6 @@ namespace Foam
 {
 
 // Forward Declarations
-class Istream;
-class Ostream;
 class labelRange;
 
 template<class T> class List;
diff --git a/src/OpenFOAM/containers/Lists/List/UListI.H b/src/OpenFOAM/containers/Lists/List/UListI.H
index 93f6a1788c..183b5e6893 100644
--- a/src/OpenFOAM/containers/Lists/List/UListI.H
+++ b/src/OpenFOAM/containers/Lists/List/UListI.H
@@ -27,7 +27,6 @@ License
 \*---------------------------------------------------------------------------*/
 
 #include "error.H"
-#include "pTraits.H"
 
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
diff --git a/src/OpenFOAM/containers/Lists/policy/ListPolicy.H b/src/OpenFOAM/containers/Lists/policy/ListPolicy.H
index 7cf2711415..aa63fc7448 100644
--- a/src/OpenFOAM/containers/Lists/policy/ListPolicy.H
+++ b/src/OpenFOAM/containers/Lists/policy/ListPolicy.H
@@ -31,10 +31,9 @@ Description
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef ListPolicy_H
-#define ListPolicy_H
+#ifndef Foam_ListPolicy_H
+#define Foam_ListPolicy_H
 
-#include "label.H"
 #include <type_traits>
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
@@ -43,9 +42,9 @@ namespace Foam
 {
 
 // Forward Declarations
+class keyType;
 class word;
 class wordRe;
-class keyType;
 
 namespace Detail
 {
@@ -58,11 +57,11 @@ namespace ListPolicy
 //
 //  Default definition: 10
 template<class T>
-struct short_length : std::integral_constant<label,10> {};
+struct short_length : std::integral_constant<int,10> {};
 
-// Could override on a per-type basis
+// Can override on a per-type basis
 // Eg,
-// template<> struct short_length<label> : std::integral_constant<label,20> {};
+// template<> struct short_length<label> : std::integral_constant<int,20> {};
 
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
@@ -75,19 +74,19 @@ struct short_length : std::integral_constant<label,10> {};
 template<class T>
 struct no_linebreak : std::is_arithmetic<T> {};
 
-// Specialization for word, wordRe, keyType
+// Specialization for word-like classes
 // These elements are normally fairly short, so ok to output a few (eg, 10)
 // of them on a single line.
 
+//- Suppress line-breaks for keyType
+template<> struct no_linebreak<keyType> : std::true_type {};
+
 //- Suppress line-breaks for word
 template<> struct no_linebreak<word> : std::true_type {};
 
 //- Suppress line-breaks for wordRe
 template<> struct no_linebreak<wordRe> : std::true_type {};
 
-//- Suppress line-breaks for keyType
-template<> struct no_linebreak<keyType> : std::true_type {};
-
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
diff --git a/src/OpenFOAM/db/IOobjects/CompactIOList/CompactIOList.H b/src/OpenFOAM/db/IOobjects/CompactIOList/CompactIOList.H
index b3357a4ee2..20312ff262 100644
--- a/src/OpenFOAM/db/IOobjects/CompactIOList/CompactIOList.H
+++ b/src/OpenFOAM/db/IOobjects/CompactIOList/CompactIOList.H
@@ -51,8 +51,6 @@ namespace Foam
 {
 
 // Forward Declarations
-class Istream;
-class Ostream;
 template<class T, class BaseType> class CompactIOList;
 
 template<class T, class BaseType> Istream& operator>>
diff --git a/src/OpenFOAM/db/IOstreams/IOstreams/InfoProxy.H b/src/OpenFOAM/db/IOstreams/IOstreams/InfoProxy.H
index d005719361..b8190bab0d 100644
--- a/src/OpenFOAM/db/IOstreams/IOstreams/InfoProxy.H
+++ b/src/OpenFOAM/db/IOstreams/IOstreams/InfoProxy.H
@@ -31,23 +31,25 @@ Description
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef InfoProxy_H
-#define InfoProxy_H
+#ifndef Foam_InfoProxy_H
+#define Foam_InfoProxy_H
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 namespace Foam
 {
 
+// Forward Declarations
 class Ostream;
 
+template<class T> class InfoProxy;
+template<class T> Ostream& operator<<(Ostream&, const InfoProxy<T>&);
+
+
 /*---------------------------------------------------------------------------*\
                            Class InfoProxy Declaration
 \*---------------------------------------------------------------------------*/
 
-template<class T> class InfoProxy;
-template<class T> Ostream& operator<<(Ostream&, const InfoProxy<T>&);
-
 template<class T>
 class InfoProxy
 {
diff --git a/src/OpenFOAM/db/IOstreams/memory/memoryStreamBuffer.H b/src/OpenFOAM/db/IOstreams/memory/memoryStreamBuffer.H
index fe72912421..4bfc1daa08 100644
--- a/src/OpenFOAM/db/IOstreams/memory/memoryStreamBuffer.H
+++ b/src/OpenFOAM/db/IOstreams/memory/memoryStreamBuffer.H
@@ -32,8 +32,8 @@ Description
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef memoryStreamBuffer_H
-#define memoryStreamBuffer_H
+#ifndef Foam_memoryStreamBuffer_H
+#define Foam_memoryStreamBuffer_H
 
 #include "UList.H"
 #include <type_traits>
@@ -44,9 +44,6 @@ Description
 namespace Foam
 {
 
-// Forward Declarations
-class Ostream;
-
 /*---------------------------------------------------------------------------*\
                           Class memorybuf Declaration
 \*---------------------------------------------------------------------------*/
diff --git a/src/OpenFOAM/db/dictionary/functionEntries/codeStream/codeStream.H b/src/OpenFOAM/db/dictionary/functionEntries/codeStream/codeStream.H
index 036c260faf..de9361190a 100644
--- a/src/OpenFOAM/db/dictionary/functionEntries/codeStream/codeStream.H
+++ b/src/OpenFOAM/db/dictionary/functionEntries/codeStream/codeStream.H
@@ -101,6 +101,7 @@ SourceFiles
 
 namespace Foam
 {
+
 // Forward Declarations
 class dlLibraryTable;
 
diff --git a/src/OpenFOAM/dimensionedTypes/dimensionedType/dimensionedType.C b/src/OpenFOAM/dimensionedTypes/dimensionedType/dimensionedType.C
index 6071afae1e..3c4d681d95 100644
--- a/src/OpenFOAM/dimensionedTypes/dimensionedType/dimensionedType.C
+++ b/src/OpenFOAM/dimensionedTypes/dimensionedType/dimensionedType.C
@@ -27,7 +27,6 @@ License
 \*---------------------------------------------------------------------------*/
 
 #include "dimensionedType.H"
-#include "pTraits.H"
 #include "dictionary.H"
 
 // * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
diff --git a/src/OpenFOAM/global/debug/debug.H b/src/OpenFOAM/global/debug/debug.H
index 3e931becc2..53fab0d2a2 100644
--- a/src/OpenFOAM/global/debug/debug.H
+++ b/src/OpenFOAM/global/debug/debug.H
@@ -43,7 +43,7 @@ SourceFiles
 namespace Foam
 {
 
-// Forward declarations
+// Forward Declarations
 class dictionary;
 class Istream;
 class Ostream;
diff --git a/src/OpenFOAM/global/debug/simpleRegIOobject.H b/src/OpenFOAM/global/debug/simpleRegIOobject.H
index 1be6091fda..d9c51e9a76 100644
--- a/src/OpenFOAM/global/debug/simpleRegIOobject.H
+++ b/src/OpenFOAM/global/debug/simpleRegIOobject.H
@@ -42,7 +42,7 @@ SourceFiles
 namespace Foam
 {
 
-// Forward declarations
+// Forward Declarations
 class Istream;
 class Ostream;
 
diff --git a/src/OpenFOAM/global/profiling/profiling.H b/src/OpenFOAM/global/profiling/profiling.H
index d2fba7f5d4..fe711bad20 100644
--- a/src/OpenFOAM/global/profiling/profiling.H
+++ b/src/OpenFOAM/global/profiling/profiling.H
@@ -52,8 +52,8 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef profiling_H
-#define profiling_H
+#ifndef Foam_profiling_H
+#define Foam_profiling_H
 
 #include "profilingTrigger.H"
 #include "IOdictionary.H"
@@ -69,7 +69,6 @@ namespace Foam
 {
 
 // Forward Declarations
-class Ostream;
 class cpuInfo;
 class memInfo;
 class profilingInformation;
diff --git a/src/OpenFOAM/matrices/Matrix/MatrixTools.H b/src/OpenFOAM/matrices/Matrix/MatrixTools.H
index 95fa5bcd59..0c61d5b1ed 100644
--- a/src/OpenFOAM/matrices/Matrix/MatrixTools.H
+++ b/src/OpenFOAM/matrices/Matrix/MatrixTools.H
@@ -34,8 +34,8 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef MatrixTools_H
-#define MatrixTools_H
+#ifndef Foam_MatrixTools_H
+#define Foam_MatrixTools_H
 
 #include "Matrix.H"
 
@@ -44,9 +44,6 @@ SourceFiles
 namespace Foam
 {
 
-// Forward declarations
-class Ostream;
-
 /*---------------------------------------------------------------------------*\
                        Namespace MatrixTools Declaration
 \*---------------------------------------------------------------------------*/
diff --git a/src/OpenFOAM/primitives/Scalar/Scalar.H b/src/OpenFOAM/primitives/Scalar/Scalar.H
index d8d41cae97..4fe5c81b66 100644
--- a/src/OpenFOAM/primitives/Scalar/Scalar.H
+++ b/src/OpenFOAM/primitives/Scalar/Scalar.H
@@ -294,6 +294,13 @@ inline bool notEqual(const Scalar a, const Scalar b)
 }
 
 
+//- Clamp scalar value to a 0-1 range
+inline Scalar clamp(const Scalar val, const Foam::zero_one)
+{
+    return (val < 0) ? 0 : (1 < val) ? 1 : val;
+}
+
+
 // Fast implementation, and with scalar promotion of upper/lower limits
 inline Scalar clamp(const Scalar& val, const Scalar& lower, const Scalar& upper)
 {
diff --git a/src/OpenFOAM/primitives/Scalar/doubleScalar/doubleScalar.H b/src/OpenFOAM/primitives/Scalar/doubleScalar/doubleScalar.H
index 5718d2d79d..fba14df589 100644
--- a/src/OpenFOAM/primitives/Scalar/doubleScalar/doubleScalar.H
+++ b/src/OpenFOAM/primitives/Scalar/doubleScalar/doubleScalar.H
@@ -35,12 +35,13 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef Foam_doubleScalar_H
-#define Foam_doubleScalar_H
+#ifndef Foam_primitives_double_H
+#define Foam_primitives_double_H
 
 #include "scalarFwd.H"
 #include "doubleFloat.H"
 #include "direction.H"
+#include "pTraits.H"
 #include "word.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
diff --git a/src/OpenFOAM/primitives/Scalar/floatScalar/floatScalar.H b/src/OpenFOAM/primitives/Scalar/floatScalar/floatScalar.H
index cb5dd78912..8d041a0111 100644
--- a/src/OpenFOAM/primitives/Scalar/floatScalar/floatScalar.H
+++ b/src/OpenFOAM/primitives/Scalar/floatScalar/floatScalar.H
@@ -35,12 +35,13 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef Foam_floatScalar_H
-#define Foam_floatScalar_H
+#ifndef Foam_primitives_float_H
+#define Foam_primitives_float_H
 
 #include "scalarFwd.H"
 #include "doubleFloat.H"
 #include "direction.H"
+#include "pTraits.H"
 #include "word.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
diff --git a/src/OpenFOAM/primitives/VectorSpace/products.H b/src/OpenFOAM/primitives/VectorSpace/products.H
index fcf9f4a464..640d53d257 100644
--- a/src/OpenFOAM/primitives/VectorSpace/products.H
+++ b/src/OpenFOAM/primitives/VectorSpace/products.H
@@ -32,8 +32,8 @@ Description
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef products_H
-#define products_H
+#ifndef Foam_products_H
+#define Foam_products_H
 
 #include "direction.H"
 #include "pTraits.H"
diff --git a/src/OpenFOAM/primitives/bools/bool/bool.H b/src/OpenFOAM/primitives/bools/bool/bool.H
index 5e37495e05..0e791d0404 100644
--- a/src/OpenFOAM/primitives/bools/bool/bool.H
+++ b/src/OpenFOAM/primitives/bools/bool/bool.H
@@ -35,18 +35,17 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef bool_H
-#define bool_H
+#ifndef Foam_primitives_bool_H
+#define Foam_primitives_bool_H
+
+#include "pTraits.H"
+#include "direction.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 namespace Foam
 {
 
-// Forward Declarations
-class Istream;
-class Ostream;
-
 // IOstream Operators
 
 //- Read bool from stream using Foam::Switch(Istream&)
@@ -58,18 +57,12 @@ Ostream& operator<<(Ostream& os, const bool b);
 //- Read bool from stream using Foam::Switch(Istream&)
 bool readBool(Istream& is);
 
-} // End namespace Foam
 
+/*---------------------------------------------------------------------------*\
+                         Specialization pTraits<bool>
+\*---------------------------------------------------------------------------*/
 
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-#include "pTraits.H"
-#include "direction.H"
-
-namespace Foam
-{
-
-// Template specialisation for pTraits<bool>
+//- Template specialisation for pTraits\<bool\>
 template<>
 class pTraits<bool>
 {
@@ -121,16 +114,10 @@ public:
     // Member Functions
 
         //- Return the value
-        operator bool() const noexcept
-        {
-            return p_;
-        }
+        operator bool() const noexcept { return p_; }
 
         //- Access the value
-        operator bool&() noexcept
-        {
-            return p_;
-        }
+        operator bool&() noexcept { return p_; }
 };
 
 
diff --git a/src/OpenFOAM/primitives/chars/char/char.H b/src/OpenFOAM/primitives/chars/char/char.H
index 7708e2be9e..959e0f075c 100644
--- a/src/OpenFOAM/primitives/chars/char/char.H
+++ b/src/OpenFOAM/primitives/chars/char/char.H
@@ -38,15 +38,13 @@ SourceFiles
 #ifndef Foam_primitives_char_H
 #define Foam_primitives_char_H
 
+#include "pTraits.H"
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 namespace Foam
 {
 
-// Forward Declarations
-class Istream;
-class Ostream;
-
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 //- Read single character
@@ -76,16 +74,9 @@ inline bool isspace(char c) noexcept
 }
 
 
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-} // End namespace Foam
-
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
-
-#include "pTraits.H"
-
-namespace Foam
-{
+/*---------------------------------------------------------------------------*\
+                         Specialization pTraits<char>
+\*---------------------------------------------------------------------------*/
 
 //- Template specialisation for pTraits\<char\>
 template<>
@@ -115,16 +106,10 @@ public:
     // Member Functions
 
         //- Return the value
-        operator char() const noexcept
-        {
-            return p_;
-        }
+        operator char() const noexcept { return p_; }
 
         //- Access the value
-        operator char&() noexcept
-        {
-            return p_;
-        }
+        operator char&() noexcept { return p_; }
 };
 
 
diff --git a/src/OpenFOAM/primitives/chars/wchar/wchar.H b/src/OpenFOAM/primitives/chars/wchar/wchar.H
index 25a80bc554..67a4b3a618 100644
--- a/src/OpenFOAM/primitives/chars/wchar/wchar.H
+++ b/src/OpenFOAM/primitives/chars/wchar/wchar.H
@@ -38,8 +38,8 @@ See also
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef wchar_H
-#define wchar_H
+#ifndef Foam_primitives_wchar_H
+#define Foam_primitives_wchar_H
 
 #include <cwchar>
 #include <string>
diff --git a/src/OpenFOAM/primitives/complex/complex.H b/src/OpenFOAM/primitives/complex/complex.H
index 459a5710bf..6fa4bc5bf0 100644
--- a/src/OpenFOAM/primitives/complex/complex.H
+++ b/src/OpenFOAM/primitives/complex/complex.H
@@ -44,7 +44,6 @@ SourceFiles
 #include "zero.H"
 #include "contiguous.H"
 #include <complex>
-#include <type_traits>
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
@@ -224,10 +223,10 @@ public:
 
 
 /*---------------------------------------------------------------------------*\
-                      Class pTraits<complex> Declaration
+                        Specialization pTraits<complex>
 \*---------------------------------------------------------------------------*/
 
-// Template specialisation for pTraits<complex>
+//- Template specialisation for pTraits<complex>
 template<>
 class pTraits<complex>
 {
@@ -288,16 +287,10 @@ public:
     // Member Functions
 
         //- Return the value
-        operator complex() const noexcept
-        {
-            return p_;
-        }
+        operator complex() const noexcept { return p_; }
 
         //- Access the value
-        operator complex&() noexcept
-        {
-            return p_;
-        }
+        operator complex&() noexcept { return p_; }
 };
 
 
diff --git a/src/OpenFOAM/primitives/direction/direction.H b/src/OpenFOAM/primitives/direction/direction.H
index 2e3ec46de1..b9f67e4370 100644
--- a/src/OpenFOAM/primitives/direction/direction.H
+++ b/src/OpenFOAM/primitives/direction/direction.H
@@ -36,21 +36,19 @@ Note
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef primitives_direction_H
-#define primitives_direction_H
+#ifndef Foam_primitives_direction_H
+#define Foam_primitives_direction_H
 
 #include <cstdint>
 #include <iostream>
 
+#include "pTraits.H"
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 namespace Foam
 {
 
-// Forward Declarations
-class Istream;
-class Ostream;
-
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 typedef uint8_t direction;
diff --git a/src/OpenFOAM/primitives/direction/directionIO.C b/src/OpenFOAM/primitives/direction/directionIO.C
index c17a3b6546..739e0b4882 100644
--- a/src/OpenFOAM/primitives/direction/directionIO.C
+++ b/src/OpenFOAM/primitives/direction/directionIO.C
@@ -47,7 +47,7 @@ Foam::Istream& Foam::operator>>(Istream& is, direction& val)
     if (!t.good())
     {
         FatalIOErrorInFunction(is)
-            << "Bad token - could not get direction"
+            << "Bad token - could not get uint8/direction"
             << exit(FatalIOError);
         is.setBad();
         return is;
@@ -60,7 +60,7 @@ Foam::Istream& Foam::operator>>(Istream& is, direction& val)
     else
     {
         FatalIOErrorInFunction(is)
-            << "Wrong token type - expected label (direction), found "
+            << "Wrong token type - expected label (uint8/direction), found "
             << t.info()
             << exit(FatalIOError);
         is.setBad();
diff --git a/src/OpenFOAM/primitives/functions/Function1/ramp/ramp.H b/src/OpenFOAM/primitives/functions/Function1/ramp/ramp.H
index 2dc4e26c17..f85f4b8881 100644
--- a/src/OpenFOAM/primitives/functions/Function1/ramp/ramp.H
+++ b/src/OpenFOAM/primitives/functions/Function1/ramp/ramp.H
@@ -100,7 +100,7 @@ protected:
         //- that forms the basis of many more complex ramp functions
         inline scalar linearRamp(const scalar t) const
         {
-            return clamp((t - start_)/duration_, 0, 1);
+            return clamp((t - start_)/duration_, zero_one{});
         }
 
 
diff --git a/src/OpenFOAM/primitives/hashes/SHA1/SHA1Digest.H b/src/OpenFOAM/primitives/hashes/SHA1/SHA1Digest.H
index f7456ef1b2..c8d0e7fa27 100644
--- a/src/OpenFOAM/primitives/hashes/SHA1/SHA1Digest.H
+++ b/src/OpenFOAM/primitives/hashes/SHA1/SHA1Digest.H
@@ -50,9 +50,9 @@ namespace Foam
 {
 
 // Forward Declarations
-class SHA1;
 class Istream;
 class Ostream;
+class SHA1;
 
 /*---------------------------------------------------------------------------*\
                          Class SHA1Digest Declaration
diff --git a/src/OpenFOAM/primitives/ints/int/int.H b/src/OpenFOAM/primitives/ints/int/int.H
index 906660fd31..48900d3c8c 100644
--- a/src/OpenFOAM/primitives/ints/int/int.H
+++ b/src/OpenFOAM/primitives/ints/int/int.H
@@ -37,6 +37,7 @@ SourceFiles
 #ifndef Foam_primitives_int_H
 #define Foam_primitives_int_H
 
+#include "int8.H"
 #include "int16.H"
 #include "int32.H"
 #include "int64.H"
diff --git a/src/OpenFOAM/primitives/ints/int16/int16.H b/src/OpenFOAM/primitives/ints/int16/int16.H
index f7abe5ea16..21587e88e6 100644
--- a/src/OpenFOAM/primitives/ints/int16/int16.H
+++ b/src/OpenFOAM/primitives/ints/int16/int16.H
@@ -27,7 +27,7 @@ Primitive
     int16_t
 
 Description
-    16bit signed integer. I/O is done via an int32.
+    16bit signed integer. I/O is done as an int32.
 
 SourceFiles
     int16.C
@@ -38,6 +38,9 @@ SourceFiles
 #define Foam_primitives_int16_H
 
 #include <cstdint>
+
+#include "direction.H"
+#include "pTraits.H"
 #include "word.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
@@ -45,10 +48,6 @@ SourceFiles
 namespace Foam
 {
 
-// Forward Declarations
-class Istream;
-class Ostream;
-
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 //- A word representation of int16 value
diff --git a/src/OpenFOAM/primitives/ints/int32/int32.H b/src/OpenFOAM/primitives/ints/int32/int32.H
index a4d83b2d6f..bd97eae76b 100644
--- a/src/OpenFOAM/primitives/ints/int32/int32.H
+++ b/src/OpenFOAM/primitives/ints/int32/int32.H
@@ -52,10 +52,6 @@ SourceFiles
 namespace Foam
 {
 
-// Forward Declarations
-class Istream;
-class Ostream;
-
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 //- A word representation of int32 value
@@ -76,6 +72,12 @@ struct nameOp<int32_t>
 };
 
 
+inline int32_t mag(const int32_t val)
+{
+    return ::abs(val);
+}
+
+
 // * * * * * * * * * * * * * * * IOstream Operators  * * * * * * * * * * * * //
 
 //- Read int32_t from stream
@@ -131,6 +133,10 @@ Ostream& operator<<(Ostream& os, const int32_t val);
 #endif
 
 
+/*---------------------------------------------------------------------------*\
+                        Specialization pTraits<int32_t>
+\*---------------------------------------------------------------------------*/
+
 //- Template specialization for pTraits<int32_t>
 template<>
 class pTraits<int32_t>
@@ -187,25 +193,13 @@ public:
     // Member Functions
 
         //- Return the value
-        operator int32_t() const noexcept
-        {
-            return p_;
-        }
+        operator int32_t() const noexcept { return p_; }
 
         //- Access the value
-        operator int32_t&() noexcept
-        {
-            return p_;
-        }
+        operator int32_t&() noexcept { return p_; }
 };
 
 
-inline int32_t mag(const int32_t val)
-{
-    return ::abs(val);
-}
-
-
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 } // End namespace Foam
diff --git a/src/OpenFOAM/primitives/ints/int64/int64.H b/src/OpenFOAM/primitives/ints/int64/int64.H
index ff77dfe2a6..49766d2621 100644
--- a/src/OpenFOAM/primitives/ints/int64/int64.H
+++ b/src/OpenFOAM/primitives/ints/int64/int64.H
@@ -52,10 +52,6 @@ SourceFiles
 namespace Foam
 {
 
-// Forward Declarations
-class Istream;
-class Ostream;
-
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 //- A word representation of int64 value
@@ -76,6 +72,12 @@ struct nameOp<int64_t>
 };
 
 
+inline int64_t mag(const int64_t val)
+{
+    return ::labs(val);
+}
+
+
 // * * * * * * * * * * * * * * * IOstream Operators  * * * * * * * * * * * * //
 
 //- Read int64_t from stream
@@ -130,6 +132,10 @@ Ostream& operator<<(Ostream& os, const int64_t val);
 #endif
 
 
+/*---------------------------------------------------------------------------*\
+                        Specialization pTraits<int64_t>
+\*---------------------------------------------------------------------------*/
+
 //- Template specialization for pTraits<int64_t>
 template<>
 class pTraits<int64_t>
@@ -186,25 +192,13 @@ public:
     // Member Functions
 
         //- Return the value
-        operator int64_t() const noexcept
-        {
-            return p_;
-        }
+        operator int64_t() const noexcept { return p_; }
 
         //- Access the value
-        operator int64_t&() noexcept
-        {
-            return p_;
-        }
+        operator int64_t&() noexcept { return p_; }
 };
 
 
-inline int64_t mag(const int64_t val)
-{
-    return ::labs(val);
-}
-
-
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 } // End namespace Foam
diff --git a/src/OpenFOAM/primitives/ints/int8/int8.C b/src/OpenFOAM/primitives/ints/int8/int8.C
new file mode 100644
index 0000000000..e411d5f992
--- /dev/null
+++ b/src/OpenFOAM/primitives/ints/int8/int8.C
@@ -0,0 +1,105 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2023 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 "int8.H"
+#include "IOstreams.H"
+
+// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
+
+const char* const Foam::pTraits<int8_t>::typeName = "int8";
+const char* const Foam::pTraits<int8_t>::componentNames[] = { "" };
+
+const int8_t Foam::pTraits<int8_t>::zero = 0;
+const int8_t Foam::pTraits<int8_t>::one = 1;
+const int8_t Foam::pTraits<int8_t>::min = INT8_MIN;
+const int8_t Foam::pTraits<int8_t>::max = INT8_MAX;
+const int8_t Foam::pTraits<int8_t>::rootMin = INT8_MIN;
+const int8_t Foam::pTraits<int8_t>::rootMax = INT8_MAX;
+
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+Foam::pTraits<int8_t>::pTraits(Istream& is)
+{
+    is >> p_;
+}
+
+
+// * * * * * * * * * * * * * * * IOstream Operators  * * * * * * * * * * * * //
+
+// int8_t Foam::readInt8(Istream& is)
+// {
+//     int8_t val(0);
+//     is >> val;
+//
+//     return val;
+// }
+
+
+Foam::Istream& Foam::operator>>(Istream& is, int8_t& val)
+{
+    token t(is);
+
+    if (!t.good())
+    {
+        FatalIOErrorInFunction(is)
+            << "Bad token - could not get int8"
+            << exit(FatalIOError);
+        is.setBad();
+        return is;
+    }
+
+    // Accept separated '-' (or '+') while expecting a number.
+    // This can arise during dictionary expansions (Eg, -$value)
+
+    if (t.isLabel())
+    {
+        val = int8_t(t.labelToken());
+    }
+    else
+    {
+        FatalIOErrorInFunction(is)
+            << "Wrong token type - expected label (int8), found "
+            << t.info() << exit(FatalIOError);
+        is.setBad();
+        return is;
+    }
+
+    is.check(FUNCTION_NAME);
+    return is;
+}
+
+
+Foam::Ostream& Foam::operator<<(Ostream& os, const int8_t val)
+{
+    os.write(label(val));
+    os.check(FUNCTION_NAME);
+    return os;
+}
+
+
+// ************************************************************************* //
diff --git a/src/OpenFOAM/primitives/ints/int8/int8.H b/src/OpenFOAM/primitives/ints/int8/int8.H
new file mode 100644
index 0000000000..734b5323a9
--- /dev/null
+++ b/src/OpenFOAM/primitives/ints/int8/int8.H
@@ -0,0 +1,154 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2023 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/>.
+
+Primitive
+    int8_t
+
+Description
+    8bit signed integer
+
+SourceFiles
+    int8.C
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef Foam_primitives_int8_H
+#define Foam_primitives_int8_H
+
+#include <cstdint>
+#include <climits>
+#include <cstdlib>
+
+#include "direction.H"
+#include "pTraits.H"
+#include "word.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+//- A word representation of uint8 value
+inline word name(const int8_t val)
+{
+    return word(std::to_string(int(val)), false); // Needs no stripping
+}
+
+
+//- A word representation of uint8 value
+template<>
+struct nameOp<int8_t>
+{
+    word operator()(const int8_t val) const
+    {
+        return word(std::to_string(int(val)), false); // Needs no stripping
+    }
+};
+
+
+// * * * * * * * * * * * * * * * IOstream Operators  * * * * * * * * * * * * //
+
+//- Read from stream (as label)
+Istream& operator>>(Istream& is, int8_t& val);
+
+//- Write to stream (as label)
+Ostream& operator<<(Ostream& os, const int8_t val);
+
+
+/*---------------------------------------------------------------------------*\
+                        Specialization pTraits<int8_t>
+\*---------------------------------------------------------------------------*/
+
+//- Template specialization for pTraits<int8_t>
+template<>
+class pTraits<int8_t>
+{
+    int8_t p_;
+
+public:
+
+    // Typedefs
+
+        //- Component type
+        typedef int8_t cmptType;
+
+
+    // Member Constants
+
+        //- Dimensionality of space
+        static constexpr direction dim = 3;
+
+        //- Rank of int8_t is 0
+        static constexpr direction rank = 0;
+
+        //- Number of components in int8_t is 1
+        static constexpr direction nComponents = 1;
+
+
+    // Static Data Members
+
+        static const char* const typeName;
+        static const char* const componentNames[];
+        static const int8_t zero;
+        static const int8_t one;
+        static const int8_t min;
+        static const int8_t max;
+        static const int8_t rootMax;
+        static const int8_t rootMin;
+
+
+    // Constructors
+
+        //- Copy construct from primitive
+        explicit pTraits(int8_t val) noexcept
+        :
+            p_(val)
+        {}
+
+        //- Read construct from Istream
+        explicit pTraits(Istream& is);
+
+
+    // Member Functions
+
+        //- Return the value
+        operator int8_t() const noexcept { return p_; }
+
+        //- Access the value
+        operator int8_t&() noexcept { return p_; }
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //
diff --git a/src/OpenFOAM/primitives/ints/uint16/uint16.H b/src/OpenFOAM/primitives/ints/uint16/uint16.H
index 7a02b0db15..14b9b249fd 100644
--- a/src/OpenFOAM/primitives/ints/uint16/uint16.H
+++ b/src/OpenFOAM/primitives/ints/uint16/uint16.H
@@ -27,7 +27,7 @@ Primitive
     uint16_t
 
 Description
-    16bit unsigned integer. I/O is done via an int32.
+    16bit unsigned integer. I/O is done as an int32.
 
 SourceFiles
     uint16.C
@@ -38,6 +38,9 @@ SourceFiles
 #define Foam_primitives_uint16_H
 
 #include <cstdint>
+
+#include "direction.H"
+#include "pTraits.H"
 #include "word.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
@@ -45,10 +48,6 @@ SourceFiles
 namespace Foam
 {
 
-// Forward Declarations
-class Istream;
-class Ostream;
-
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 //- A word representation of uint16 value
diff --git a/src/OpenFOAM/primitives/ints/uint32/uint32.H b/src/OpenFOAM/primitives/ints/uint32/uint32.H
index ecb10c92ce..ba0e7e5887 100644
--- a/src/OpenFOAM/primitives/ints/uint32/uint32.H
+++ b/src/OpenFOAM/primitives/ints/uint32/uint32.H
@@ -52,10 +52,6 @@ SourceFiles
 namespace Foam
 {
 
-// Forward Declarations
-class Istream;
-class Ostream;
-
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 //- A word representation of uint32 value
@@ -120,6 +116,11 @@ inline bool read(const std::string& str, uint32_t& val)
 Istream& operator>>(Istream& is, uint32_t& val);
 Ostream& operator<<(Ostream& os, const uint32_t val);
 
+
+/*---------------------------------------------------------------------------*\
+                       Specialization pTraits<uint32_t>
+\*---------------------------------------------------------------------------*/
+
 //- Template specialization for pTraits<uint32_t>
 template<>
 class pTraits<uint32_t>
@@ -173,16 +174,10 @@ public:
     // Member Functions
 
         //- Return the value
-        operator uint32_t() const noexcept
-        {
-            return p_;
-        }
+        operator uint32_t() const noexcept { return p_; }
 
         //- Access the value
-        operator uint32_t&() noexcept
-        {
-            return p_;
-        }
+        operator uint32_t&() noexcept { return p_; }
 };
 
 
diff --git a/src/OpenFOAM/primitives/ints/uint64/uint64.H b/src/OpenFOAM/primitives/ints/uint64/uint64.H
index 90c48e793d..98e6346d6b 100644
--- a/src/OpenFOAM/primitives/ints/uint64/uint64.H
+++ b/src/OpenFOAM/primitives/ints/uint64/uint64.H
@@ -52,10 +52,6 @@ SourceFiles
 namespace Foam
 {
 
-// Forward Declarations
-class Istream;
-class Ostream;
-
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 //- A word representation of uint64 value
@@ -129,6 +125,10 @@ Ostream& operator<<(Ostream& os, const uint64_t val);
 #endif
 
 
+/*---------------------------------------------------------------------------*\
+                       Specialization pTraits<uint64_t>
+\*---------------------------------------------------------------------------*/
+
 //- Template specialization for pTraits<uint64_t>
 template<>
 class pTraits<uint64_t>
@@ -182,16 +182,10 @@ public:
     // Member Functions
 
         //- Return the value
-        operator uint64_t() const noexcept
-        {
-            return p_;
-        }
+        operator uint64_t() const noexcept { return p_; }
 
         //- Access the value
-        operator uint64_t&() noexcept
-        {
-            return p_;
-        }
+        operator uint64_t&() noexcept { return p_; }
 };
 
 
diff --git a/src/OpenFOAM/primitives/ints/uint8/uint8.C b/src/OpenFOAM/primitives/ints/uint8/uint8.C
index 83501ca834..ad217c1572 100644
--- a/src/OpenFOAM/primitives/ints/uint8/uint8.C
+++ b/src/OpenFOAM/primitives/ints/uint8/uint8.C
@@ -26,6 +26,7 @@ License
 \*---------------------------------------------------------------------------*/
 
 #include "uint8.H"
+#include "IOstreams.H"
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
@@ -48,4 +49,17 @@ Foam::pTraits<uint8_t>::pTraits(Istream& is)
 }
 
 
+// * * * * * * * * * * * * * * * IOstream Operators  * * * * * * * * * * * * //
+
+uint8_t Foam::readUint8(Istream& is)
+{
+    uint8_t val(0);
+    is >> val;
+
+    return val;
+}
+
+// IO operators are identical to direction, which is uint8_t
+
+
 // ************************************************************************* //
diff --git a/src/OpenFOAM/primitives/ints/uint8/uint8.H b/src/OpenFOAM/primitives/ints/uint8/uint8.H
index 759dcc76d0..b17d19f729 100644
--- a/src/OpenFOAM/primitives/ints/uint8/uint8.H
+++ b/src/OpenFOAM/primitives/ints/uint8/uint8.H
@@ -31,7 +31,6 @@ Description
 
 SourceFiles
     uint8.C
-    uint8IO.C
 
 \*---------------------------------------------------------------------------*/
 
@@ -51,10 +50,6 @@ SourceFiles
 namespace Foam
 {
 
-// Forward Declarations
-class Istream;
-class Ostream;
-
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 //- A word representation of uint8 value
@@ -83,7 +78,9 @@ uint8_t readUint8(Istream& is);
 // IO operators are identical to direction, which is uint8_t
 
 
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+/*---------------------------------------------------------------------------*\
+                        Specialization pTraits<uint8_t>
+\*---------------------------------------------------------------------------*/
 
 //- Template specialization for pTraits<uint8_t>
 template<>
diff --git a/src/OpenFOAM/primitives/ints/uint8/uint8IO.C b/src/OpenFOAM/primitives/ints/uint8/uint8IO.C
deleted file mode 100644
index b81239fe15..0000000000
--- a/src/OpenFOAM/primitives/ints/uint8/uint8IO.C
+++ /dev/null
@@ -1,44 +0,0 @@
-/*---------------------------------------------------------------------------*\
-  =========                 |
-  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
-   \\    /   O peration     |
-    \\  /    A nd           | www.openfoam.com
-     \\/     M anipulation  |
--------------------------------------------------------------------------------
-    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/>.
-
-\*---------------------------------------------------------------------------*/
-
-#include "uint8.H"
-#include "IOstreams.H"
-
-// * * * * * * * * * * * * * * * IOstream Operators  * * * * * * * * * * * * //
-
-uint8_t Foam::readUint8(Istream& is)
-{
-    uint8_t val(0);
-    is >> val;
-
-    return val;
-}
-
-// IO operators are identical to direction, which is uint8_t
-
-
-// ************************************************************************* //
diff --git a/src/OpenFOAM/primitives/random/Random/Random.H b/src/OpenFOAM/primitives/random/Random/Random.H
index 98fbfe092c..8669379423 100644
--- a/src/OpenFOAM/primitives/random/Random/Random.H
+++ b/src/OpenFOAM/primitives/random/Random/Random.H
@@ -37,8 +37,8 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef Random_H
-#define Random_H
+#ifndef Foam_Random_H
+#define Foam_Random_H
 
 #include "Rand48.H"
 #include "label.H"
diff --git a/src/OpenFOAM/primitives/ranges/labelRange/labelRanges.H b/src/OpenFOAM/primitives/ranges/labelRange/labelRanges.H
index 231efe2073..c2754bf2f8 100644
--- a/src/OpenFOAM/primitives/ranges/labelRange/labelRanges.H
+++ b/src/OpenFOAM/primitives/ranges/labelRange/labelRanges.H
@@ -47,8 +47,6 @@ namespace Foam
 {
 
 // Forward Declarations
-class Istream;
-class Ostream;
 class labelRanges;
 Istream& operator>>(Istream& is, labelRanges& ranges);
 Ostream& operator<<(Ostream& is, const labelRanges& ranges);
diff --git a/src/OpenFOAM/primitives/ranges/scalarRange/scalarRange.H b/src/OpenFOAM/primitives/ranges/scalarRange/scalarRange.H
index f105cba061..172b27fe0b 100644
--- a/src/OpenFOAM/primitives/ranges/scalarRange/scalarRange.H
+++ b/src/OpenFOAM/primitives/ranges/scalarRange/scalarRange.H
@@ -56,7 +56,6 @@ namespace Foam
 
 // Forward Declarations
 class scalarRange;
-class Ostream;
 template<class T> class MinMax;
 
 Ostream& operator<<(Ostream& os, const scalarRange& range);
diff --git a/src/OpenFOAM/primitives/ranges/sliceRange/sliceRange.H b/src/OpenFOAM/primitives/ranges/sliceRange/sliceRange.H
index 0dc19adaf3..d6f974b42e 100644
--- a/src/OpenFOAM/primitives/ranges/sliceRange/sliceRange.H
+++ b/src/OpenFOAM/primitives/ranges/sliceRange/sliceRange.H
@@ -35,8 +35,8 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef sliceRange_H
-#define sliceRange_H
+#ifndef Foam_sliceRange_H
+#define Foam_sliceRange_H
 
 #include "label.H"
 #include <iterator>
@@ -47,8 +47,6 @@ namespace Foam
 {
 
 // Forward Declarations
-class Istream;
-class Ostream;
 template<class T> class List;
 template<class T, unsigned N> class FixedList;
 
diff --git a/src/OpenFOAM/primitives/spatialVectorAlgebra/spatialTransform/spatialTransform.H b/src/OpenFOAM/primitives/spatialVectorAlgebra/spatialTransform/spatialTransform.H
index d9085f4de3..764a419f94 100644
--- a/src/OpenFOAM/primitives/spatialVectorAlgebra/spatialTransform/spatialTransform.H
+++ b/src/OpenFOAM/primitives/spatialVectorAlgebra/spatialTransform/spatialTransform.H
@@ -54,11 +54,7 @@ SourceFiles
 namespace Foam
 {
 
-// Forward declaration of classes
-class Istream;
-class Ostream;
-
-// Forward declaration of friend functions and operators
+// Forward Declarations
 class spatialTransform;
 Istream& operator>>(Istream&, spatialTransform&);
 Ostream& operator<<(Ostream&, const spatialTransform&);
diff --git a/src/OpenFOAM/primitives/traits/contiguous.H b/src/OpenFOAM/primitives/traits/contiguous.H
index b42493436a..b0cde4607b 100644
--- a/src/OpenFOAM/primitives/traits/contiguous.H
+++ b/src/OpenFOAM/primitives/traits/contiguous.H
@@ -5,7 +5,6 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2011-2016 OpenFOAM Foundation
     Copyright (C) 2018-2019 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
@@ -62,8 +61,8 @@ Description
 #ifndef Foam_contiguous_H
 #define Foam_contiguous_H
 
-#include "scalarFwd.H"
 #include "labelFwd.H"
+#include "scalarFwd.H"
 #include <type_traits>
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
@@ -75,26 +74,17 @@ namespace Foam
 
 // Base definition for (integral | floating-point) as contiguous
 template<class T>
-struct is_contiguous
-:
-    std::is_arithmetic<T>
-{};
+struct is_contiguous : std::is_arithmetic<T> {};
 
 
 // Base definition for 'label'
 template<class T>
-struct is_contiguous_label
-:
-    std::is_same<T, label>
-{};
+struct is_contiguous_label : std::is_same<T, label> {};
 
 
 // Base definition for 'scalar'
 template<class T>
-struct is_contiguous_scalar
-:
-    std::is_same<T, scalar>
-{};
+struct is_contiguous_scalar : std::is_same<T, scalar> {};
 
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
diff --git a/src/OpenFOAM/primitives/traits/one.H b/src/OpenFOAM/primitives/traits/one.H
index 966f86ceb1..eedd533011 100644
--- a/src/OpenFOAM/primitives/traits/one.H
+++ b/src/OpenFOAM/primitives/traits/one.H
@@ -51,7 +51,6 @@ namespace Foam
 {
 
 // Forward Declarations
-class one;
 class Istream;
 class Ostream;
 
@@ -63,11 +62,11 @@ class one
 {
 public:
 
+    //- The value type
     typedef one value_type;
 
     // Forward Declarations
     class minus;
-    class null;
 
     //- Default construct
     constexpr one() noexcept {}
@@ -113,6 +112,7 @@ class one::minus
 {
 public:
 
+    //- The value type
     typedef minus value_type;
 
     //- Default construct
@@ -148,27 +148,6 @@ public:
 };
 
 
-/*---------------------------------------------------------------------------*\
-                          Class one::null Declaration
-\*---------------------------------------------------------------------------*/
-
-//- A Foam::one class with a null output adapter.
-class one::null
-:
-    public one
-{
-public:
-
-    typedef null value_type;
-
-    //- Default construct
-    constexpr null() noexcept {}
-
-    //- Construct from Istream consumes no content.
-    explicit constexpr null(Istream&) noexcept {}
-};
-
-
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 //- Global one (1)
@@ -188,12 +167,6 @@ inline constexpr Istream& operator>>(Istream& is, one::minus&) noexcept
     return is;
 }
 
-//- Write to Ostream emits no content.
-inline constexpr Ostream& operator<<(Ostream& os, const one::null&) noexcept
-{
-    return os;
-}
-
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
diff --git a/src/OpenFOAM/primitives/traits/pTraits.H b/src/OpenFOAM/primitives/traits/pTraits.H
index f49db8c1f1..d8e219647f 100644
--- a/src/OpenFOAM/primitives/traits/pTraits.H
+++ b/src/OpenFOAM/primitives/traits/pTraits.H
@@ -46,6 +46,7 @@ namespace Foam
 
 // Forward Declarations
 class Istream;
+class Ostream;
 
 /*---------------------------------------------------------------------------*\
                            Class pTraits Declaration
@@ -76,6 +77,14 @@ public:
 };
 
 
+/*---------------------------------------------------------------------------*\
+                          Class zero_one Declaration
+\*---------------------------------------------------------------------------*/
+
+//- Represents 0/1 range or concept. Used for tagged dispatch or clamping
+class zero_one {};
+
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 } // End namespace Foam
diff --git a/src/OpenFOAM/primitives/traits/zero.H b/src/OpenFOAM/primitives/traits/zero.H
index 56681d1fc3..838aea7af9 100644
--- a/src/OpenFOAM/primitives/traits/zero.H
+++ b/src/OpenFOAM/primitives/traits/zero.H
@@ -52,8 +52,6 @@ namespace Foam
 {
 
 // Forward Declarations
-class zero;
-class zero_one;
 class Istream;
 class Ostream;
 
@@ -65,6 +63,7 @@ class zero
 {
 public:
 
+    //- The value type
     typedef zero value_type;
 
     // Forward Declarations
@@ -133,24 +132,6 @@ public:
 };
 
 
-/*---------------------------------------------------------------------------*\
-                          Class zero_one Declaration
-\*---------------------------------------------------------------------------*/
-
-//- Represents 0/1 concept, eg for tagged dispatch
-class zero_one
-{
-public:
-    typedef zero_one value_type;
-
-    //- Default construct
-    constexpr zero_one() noexcept {}
-
-    //- Construct from Istream consumes no content.
-    explicit constexpr zero_one(Istream&) noexcept {}
-};
-
-
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 //- Global zero (0)
diff --git a/src/finiteArea/faMatrices/faMatrix/faMatrix.H b/src/finiteArea/faMatrices/faMatrix/faMatrix.H
index e5b6dfae97..1d778a964d 100644
--- a/src/finiteArea/faMatrices/faMatrix/faMatrix.H
+++ b/src/finiteArea/faMatrices/faMatrix/faMatrix.H
@@ -49,7 +49,6 @@ Author
 #include "tmp.H"
 #include "autoPtr.H"
 #include "dimensionedTypes.H"
-#include "zero.H"
 #include "className.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
diff --git a/src/finiteArea/interpolation/edgeInterpolation/schemes/Gamma/Gamma.H b/src/finiteArea/interpolation/edgeInterpolation/schemes/Gamma/Gamma.H
index 80b118a7e4..39b547745d 100644
--- a/src/finiteArea/interpolation/edgeInterpolation/schemes/Gamma/Gamma.H
+++ b/src/finiteArea/interpolation/edgeInterpolation/schemes/Gamma/Gamma.H
@@ -110,7 +110,7 @@ public:
         gradcf = stabilise(gradcf, SMALL);
 
         scalar phict = 1 - 0.5*gradf/gradcf;
-        scalar limiter = clamp(phict/k_, 0, 1);
+        scalar limiter = clamp(phict/k_, zero_one{});
 
         return lerp(udWeight, cdWeight, limiter);
     }
diff --git a/src/finiteVolume/fields/fvPatchFields/derived/turbulentDFSEMInlet/eddy/eddy.H b/src/finiteVolume/fields/fvPatchFields/derived/turbulentDFSEMInlet/eddy/eddy.H
index ad6e3ebe2a..1a852a2dd2 100644
--- a/src/finiteVolume/fields/fvPatchFields/derived/turbulentDFSEMInlet/eddy/eddy.H
+++ b/src/finiteVolume/fields/fvPatchFields/derived/turbulentDFSEMInlet/eddy/eddy.H
@@ -52,10 +52,8 @@ SourceFiles
 namespace Foam
 {
 
-// Forward declarations
+// Forward Declarations
 class eddy;
-class Istream;
-class Ostream;
 
 bool operator==(const eddy& a, const eddy& b);
 bool operator!=(const eddy& a, const eddy& b);
diff --git a/src/finiteVolume/finiteVolume/fvm/fvmLaplacian.H b/src/finiteVolume/finiteVolume/fvm/fvmLaplacian.H
index 1983b4fd68..d50feb2455 100644
--- a/src/finiteVolume/finiteVolume/fvm/fvmLaplacian.H
+++ b/src/finiteVolume/finiteVolume/fvm/fvmLaplacian.H
@@ -40,7 +40,6 @@ SourceFiles
 #include "volFieldsFwd.H"
 #include "surfaceFieldsFwd.H"
 #include "fvMatrix.H"
-#include "zero.H"
 #include "one.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
diff --git a/src/finiteVolume/fvMatrices/fvMatrix/fvMatrix.H b/src/finiteVolume/fvMatrices/fvMatrix/fvMatrix.H
index c6021a514d..9f4b4b3448 100644
--- a/src/finiteVolume/fvMatrices/fvMatrix/fvMatrix.H
+++ b/src/finiteVolume/fvMatrices/fvMatrix/fvMatrix.H
@@ -49,7 +49,6 @@ SourceFiles
 #include "tmp.H"
 #include "autoPtr.H"
 #include "dimensionedTypes.H"
-#include "zero.H"
 #include "className.H"
 #include "lduPrimitiveMeshAssembly.H"
 #include "lduMesh.H"
diff --git a/src/finiteVolume/fvMatrices/solvers/MULES/MULES.H b/src/finiteVolume/fvMatrices/solvers/MULES/MULES.H
index 13bef2f37c..074affd714 100644
--- a/src/finiteVolume/fvMatrices/solvers/MULES/MULES.H
+++ b/src/finiteVolume/fvMatrices/solvers/MULES/MULES.H
@@ -49,7 +49,6 @@ SourceFiles
 #include "surfaceFieldsFwd.H"
 #include "primitiveFieldsFwd.H"
 #include "geometricOneField.H"
-#include "zero.H"
 #include "zeroField.H"
 #include "UPtrList.H"
 #include "HashSet.H"
diff --git a/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/Gamma/Gamma.H b/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/Gamma/Gamma.H
index 5996e45d4b..8babe7daaf 100644
--- a/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/Gamma/Gamma.H
+++ b/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/Gamma/Gamma.H
@@ -97,7 +97,7 @@ public:
             faceFlux, phiP, phiN, gradcP, gradcN, d
         );
 
-        return clamp(phict/k_, 0, 1);
+        return clamp(phict/k_, zero_one{});
     }
 };
 
diff --git a/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/Minmod/Minmod.H b/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/Minmod/Minmod.H
index 91d05ea146..12c2b8f41e 100644
--- a/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/Minmod/Minmod.H
+++ b/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/Minmod/Minmod.H
@@ -81,7 +81,7 @@ public:
             faceFlux, phiP, phiN, gradcP, gradcN, d
         );
 
-        return clamp(r, 0, 1);
+        return clamp(r, zero_one{});
     }
 };
 
diff --git a/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/Phi/Phi.H b/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/Phi/Phi.H
index 2b3ef8f7da..8ad1a516ea 100644
--- a/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/Phi/Phi.H
+++ b/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/Phi/Phi.H
@@ -107,7 +107,7 @@ public:
             ((faceFlux - phiU)/stabilise(phiCD - phiU, SMALL) + k_);
 
         // Limit the limiter between upwind and central
-        return clamp(PLimiter, 0, 1);
+        return clamp(PLimiter, zero_one{});
     }
 };
 
diff --git a/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/filteredLinear2/filteredLinear2.H b/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/filteredLinear2/filteredLinear2.H
index 9378fd1a01..9bebf3f2fd 100644
--- a/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/filteredLinear2/filteredLinear2.H
+++ b/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/filteredLinear2/filteredLinear2.H
@@ -141,7 +141,7 @@ public:
         }
 
         // Limit the limiter between linear and upwind
-        return clamp(limiter, 0, 1);
+        return clamp(limiter, zero_one{});
     }
 };
 
diff --git a/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/filteredLinear2/filteredLinear2V.H b/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/filteredLinear2/filteredLinear2V.H
index e8dcf7a6aa..000863bb4f 100644
--- a/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/filteredLinear2/filteredLinear2V.H
+++ b/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/filteredLinear2/filteredLinear2V.H
@@ -143,7 +143,7 @@ public:
         }
 
         // Limit the limiter between linear and upwind
-        return clamp(limiter, 0, 1);
+        return clamp(limiter, zero_one{});
     }
 };
 
diff --git a/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/filteredLinear3/filteredLinear3.H b/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/filteredLinear3/filteredLinear3.H
index 043a0e5630..6de51de72e 100644
--- a/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/filteredLinear3/filteredLinear3.H
+++ b/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/filteredLinear3/filteredLinear3.H
@@ -108,7 +108,7 @@ public:
         scalar limiter = 1 - k_*(dN - df)*(dP - df)/max(sqr(dN + dP), SMALL);
 
         // Limit the limiter between linear and upwind
-        return clamp(limiter, 0, 1);
+        return clamp(limiter, zero_one{});
     }
 };
 
diff --git a/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/filteredLinear3/filteredLinear3V.H b/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/filteredLinear3/filteredLinear3V.H
index d69562b2e5..0aa6b9c5a7 100644
--- a/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/filteredLinear3/filteredLinear3V.H
+++ b/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/filteredLinear3/filteredLinear3V.H
@@ -110,7 +110,7 @@ public:
         scalar limiter = 1 - k_*(dN - df)*(dP - df)/max(sqr(dN + dP), SMALL);
 
         // Limit the limiter between linear and upwind
-        return clamp(limiter, 0, 1);
+        return clamp(limiter, zero_one{});
     }
 };
 
diff --git a/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/limitedLinear/limitedLinear.H b/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/limitedLinear/limitedLinear.H
index 159bcc695e..f9daec4d52 100644
--- a/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/limitedLinear/limitedLinear.H
+++ b/src/finiteVolume/interpolation/surfaceInterpolation/limitedSchemes/limitedLinear/limitedLinear.H
@@ -97,7 +97,7 @@ public:
             faceFlux, phiP, phiN, gradcP, gradcN, d
         );
 
-        return clamp(twoByk_*r, 0, 1);
+        return clamp(twoByk_*r, zero_one{});
     }
 };
 
diff --git a/src/finiteVolume/interpolation/surfaceInterpolation/schemes/CoBlended/CoBlended.H b/src/finiteVolume/interpolation/surfaceInterpolation/schemes/CoBlended/CoBlended.H
index 80bd3add72..fd7f661afb 100644
--- a/src/finiteVolume/interpolation/surfaceInterpolation/schemes/CoBlended/CoBlended.H
+++ b/src/finiteVolume/interpolation/surfaceInterpolation/schemes/CoBlended/CoBlended.H
@@ -36,7 +36,7 @@ Description
     face-based Courant number and the lower and upper Courant number limits
     supplied:
     \f[
-        weight = 1 - clamp((Co - Co1)/(Co2 - Co1), 0, 1)
+        weight = 1 - clamp((Co - Co1)/(Co2 - Co1), zero_one{})
     \f]
     where
     \vartable
diff --git a/src/functionObjects/field/extractEulerianParticles/eulerianParticle/eulerianParticle.H b/src/functionObjects/field/extractEulerianParticles/eulerianParticle/eulerianParticle.H
index cbc946a568..561262604f 100644
--- a/src/functionObjects/field/extractEulerianParticles/eulerianParticle/eulerianParticle.H
+++ b/src/functionObjects/field/extractEulerianParticles/eulerianParticle/eulerianParticle.H
@@ -49,16 +49,13 @@ SourceFiles
 
 namespace Foam
 {
-// Forward Declarations
-class Istream;
-class Ostream;
-
 namespace functionObjects
 {
+    // Forward Declarations
     class eulerianParticle;
 }
 
-// Forward declaration of friend functions and operators
+// Forward Declarations
 Istream& operator>>(Istream&, functionObjects::eulerianParticle&);
 Ostream& operator<<(Ostream&, const functionObjects::eulerianParticle&);
 
diff --git a/src/functionObjects/field/fieldAverage/fieldAverageItem/fieldAverageItem.H b/src/functionObjects/field/fieldAverage/fieldAverageItem/fieldAverageItem.H
index 4ad0ea958e..171a4eeb74 100644
--- a/src/functionObjects/field/fieldAverage/fieldAverageItem/fieldAverageItem.H
+++ b/src/functionObjects/field/fieldAverage/fieldAverageItem/fieldAverageItem.H
@@ -92,15 +92,13 @@ SourceFiles
 namespace Foam
 {
 
-// Forward declaration of classes
-class Istream;
-class Ostream;
+// Forward Declarations
 class objectRegistry;
 
 namespace functionObjects
 {
 
-// Forward declaration of friend functions and operators
+// Forward Declarations
 class fieldAverageItem;
 Istream& operator>>(Istream&, fieldAverageItem&);
 Ostream& operator<<(Ostream&, const fieldAverageItem&);
diff --git a/src/functionObjects/field/fieldValues/surfaceFieldValue/surfaceFieldValue.C b/src/functionObjects/field/fieldValues/surfaceFieldValue/surfaceFieldValue.C
index e4091007a8..44bfc81834 100644
--- a/src/functionObjects/field/fieldValues/surfaceFieldValue/surfaceFieldValue.C
+++ b/src/functionObjects/field/fieldValues/surfaceFieldValue/surfaceFieldValue.C
@@ -670,7 +670,7 @@ Foam::functionObjects::fieldValues::surfaceFieldValue::processValues
             // Uniformity index
             const scalar ui = 1 - numer/(2*mag(mean*areaTotal) + ROOTVSMALL);
 
-            return clamp(ui, 0, 1);
+            return clamp(ui, zero_one{});
         }
 
         default:
@@ -756,7 +756,7 @@ Foam::functionObjects::fieldValues::surfaceFieldValue::processValues
             // Uniformity index
             const scalar ui = 1 - numer/(2*mag(mean*areaTotal) + ROOTVSMALL);
 
-            return vector(clamp(ui, 0, 1), 0, 0);
+            return vector(clamp(ui, zero_one{}), 0, 0);
         }
 
         default:
diff --git a/src/functionObjects/field/stabilityBlendingFactor/stabilityBlendingFactor.H b/src/functionObjects/field/stabilityBlendingFactor/stabilityBlendingFactor.H
index 541553c734..a09b2cc763 100644
--- a/src/functionObjects/field/stabilityBlendingFactor/stabilityBlendingFactor.H
+++ b/src/functionObjects/field/stabilityBlendingFactor/stabilityBlendingFactor.H
@@ -152,7 +152,7 @@ Description
     For option 6, the following relation is used:
 
     \f[
-        fCoWeight = clamp((Co - Co1)/(Co2 - Co1), 0, 1)
+        fCoWeight = clamp((Co - Co1)/(Co2 - Co1), zero_one{});
     \f]
 
     where
diff --git a/src/fvOptions/sources/derived/solidificationMeltingSource/solidificationMeltingSource.C b/src/fvOptions/sources/derived/solidificationMeltingSource/solidificationMeltingSource.C
index 2154433865..cf55b450bc 100644
--- a/src/fvOptions/sources/derived/solidificationMeltingSource/solidificationMeltingSource.C
+++ b/src/fvOptions/sources/derived/solidificationMeltingSource/solidificationMeltingSource.C
@@ -147,7 +147,7 @@ void Foam::fv::solidificationMeltingSource::update(const volScalarField& Cp)
         scalar Cpc = Cp[celli];
         scalar alpha1New = alpha1_[celli] + relax_*Cpc*(Tc - Tmelt_)/L_;
 
-        alpha1_[celli] = clamp(alpha1New, 0, 1);
+        alpha1_[celli] = clamp(alpha1New, zero_one{});
         deltaT_[i] = Tc - Tmelt_;
     }
 
diff --git a/src/lagrangian/distributionModels/binned/binned.H b/src/lagrangian/distributionModels/binned/binned.H
index 20e36899ab..86a0fc13bb 100644
--- a/src/lagrangian/distributionModels/binned/binned.H
+++ b/src/lagrangian/distributionModels/binned/binned.H
@@ -95,16 +95,13 @@ SourceFiles
 namespace Foam
 {
 
-// Forward declaration of classes
-class Istream;
-class Ostream;
-
 namespace distributionModels
 {
+    // Forward Declarations
     class binned;
 }
 
-// Forward declaration of friend functions and operators
+// Forward Declarations
 Istream& operator>>(Istream&, distributionModels::binned&);
 Ostream& operator<<(Ostream&, const distributionModels::binned&);
 
diff --git a/src/lagrangian/distributionModels/general/general.H b/src/lagrangian/distributionModels/general/general.H
index e3f41e8b16..66e9e20d9e 100644
--- a/src/lagrangian/distributionModels/general/general.H
+++ b/src/lagrangian/distributionModels/general/general.H
@@ -106,17 +106,13 @@ SourceFiles
 
 namespace Foam
 {
-
-// Forward declaration of classes
-class Istream;
-class Ostream;
-
 namespace distributionModels
 {
+    // Forward Declarations
     class general;
 }
 
-// Forward declaration of friend functions and operators
+// Forward Declarations
 Istream& operator>>(Istream&, distributionModels::general&);
 Ostream& operator<<(Ostream&, const distributionModels::general&);
 
diff --git a/src/lagrangian/intermediate/submodels/Kinematic/ParticleForces/Drag/DistortedSphereDrag/DistortedSphereDragForce.C b/src/lagrangian/intermediate/submodels/Kinematic/ParticleForces/Drag/DistortedSphereDrag/DistortedSphereDragForce.C
index 5d4502bade..767d0bde65 100644
--- a/src/lagrangian/intermediate/submodels/Kinematic/ParticleForces/Drag/DistortedSphereDrag/DistortedSphereDragForce.C
+++ b/src/lagrangian/intermediate/submodels/Kinematic/ParticleForces/Drag/DistortedSphereDrag/DistortedSphereDragForce.C
@@ -84,7 +84,7 @@ Foam::forceSuSp Foam::DistortedSphereDragForce<CloudType>::calcCoupled
 ) const
 {
     // Limit the drop distortion to y=0 (sphere) and y=1 (disk)
-    const scalar y = clamp(p.y(), 0, 1);
+    const scalar y = clamp(p.y(), zero_one{});
 
     // (LMR:Eq. 10)
     return
diff --git a/src/lagrangian/spray/parcels/Templates/SprayParcel/SprayParcel.C b/src/lagrangian/spray/parcels/Templates/SprayParcel/SprayParcel.C
index 8c3809b23e..df462de0dc 100644
--- a/src/lagrangian/spray/parcels/Templates/SprayParcel/SprayParcel.C
+++ b/src/lagrangian/spray/parcels/Templates/SprayParcel/SprayParcel.C
@@ -361,7 +361,7 @@ Foam::scalar Foam::SprayParcel<ParcelType>::chi
         }
     }
 
-    return clamp(chi, 0, 1);
+    return clamp(chi, zero_one{});
 }
 
 
diff --git a/src/lumpedPointMotion/movement/lumpedPointMovement.C b/src/lumpedPointMotion/movement/lumpedPointMovement.C
index 7f12b91abb..437397fd48 100644
--- a/src/lumpedPointMotion/movement/lumpedPointMovement.C
+++ b/src/lumpedPointMotion/movement/lumpedPointMovement.C
@@ -257,7 +257,7 @@ void Foam::lumpedPointMovement::readDict(const dictionary& dict)
     }
 
     relax_ = dict.getOrDefault<scalar>("relax", 1);
-    relax_ = clamp(relax_, 0, 1);
+    relax_ = clamp(relax_, zero_one{});
 
     forcesDict_.merge(dict.subOrEmptyDict("forces"));
 
diff --git a/src/lumpedPointMotion/state/lumpedPointState.H b/src/lumpedPointMotion/state/lumpedPointState.H
index 68dbe37782..09b247fe6f 100644
--- a/src/lumpedPointMotion/state/lumpedPointState.H
+++ b/src/lumpedPointMotion/state/lumpedPointState.H
@@ -77,10 +77,6 @@ SourceFiles
 namespace Foam
 {
 
-// Forward Declarations
-class Istream;
-class Ostream;
-
 /*---------------------------------------------------------------------------*\
                       Class lumpedPointState Declaration
 \*---------------------------------------------------------------------------*/
diff --git a/src/mesh/blockMesh/gradingDescriptor/gradingDescriptor.H b/src/mesh/blockMesh/gradingDescriptor/gradingDescriptor.H
index 6199468102..90f1aac352 100644
--- a/src/mesh/blockMesh/gradingDescriptor/gradingDescriptor.H
+++ b/src/mesh/blockMesh/gradingDescriptor/gradingDescriptor.H
@@ -58,8 +58,6 @@ namespace Foam
 {
 
 // Forward Declarations
-class Istream;
-class Ostream;
 class gradingDescriptor;
 class gradingDescriptors;
 
diff --git a/src/mesh/blockMesh/gradingDescriptor/gradingDescriptors.H b/src/mesh/blockMesh/gradingDescriptor/gradingDescriptors.H
index dbc8810a93..a9020031ab 100644
--- a/src/mesh/blockMesh/gradingDescriptor/gradingDescriptors.H
+++ b/src/mesh/blockMesh/gradingDescriptor/gradingDescriptors.H
@@ -48,7 +48,6 @@ namespace Foam
 {
 
 // Forward Declarations
-class Istream;
 class gradingDescriptors;
 Istream& operator>>(Istream& is, gradingDescriptors& gd);
 
diff --git a/src/mesh/snappyHexMesh/snappyHexMeshDriver/PointIntegrateData/PointIntegrateData.H b/src/mesh/snappyHexMesh/snappyHexMeshDriver/PointIntegrateData/PointIntegrateData.H
index afbccd3b24..89e1988041 100644
--- a/src/mesh/snappyHexMesh/snappyHexMeshDriver/PointIntegrateData/PointIntegrateData.H
+++ b/src/mesh/snappyHexMesh/snappyHexMeshDriver/PointIntegrateData/PointIntegrateData.H
@@ -37,14 +37,14 @@ SourceFiles
 #ifndef PointIntegrateData_H
 #define PointIntegrateData_H
 
+#include "UList.H"
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 namespace Foam
 {
 
 // Forward Declarations
-class Istream;
-class Ostream;
 template<class DataType> class PointIntegrateData;
 
 template<class DataType>
diff --git a/src/meshTools/algorithms/PatchEdgeFaceWave/patchEdgeFaceInfo.H b/src/meshTools/algorithms/PatchEdgeFaceWave/patchEdgeFaceInfo.H
index 4ea497b8f9..7ba9b4add5 100644
--- a/src/meshTools/algorithms/PatchEdgeFaceWave/patchEdgeFaceInfo.H
+++ b/src/meshTools/algorithms/PatchEdgeFaceWave/patchEdgeFaceInfo.H
@@ -38,11 +38,10 @@ SourceFiles
 #ifndef patchEdgeFaceInfo_H
 #define patchEdgeFaceInfo_H
 
-#include "point.H"
 #include "label.H"
 #include "scalar.H"
+#include "point.H"
 #include "tensor.H"
-#include "pTraits.H"
 #include "primitivePatch.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
diff --git a/src/meshTools/algorithms/PointEdgeWave/PointData.H b/src/meshTools/algorithms/PointEdgeWave/PointData.H
index cc4a3d715f..9f27a1f7e1 100644
--- a/src/meshTools/algorithms/PointEdgeWave/PointData.H
+++ b/src/meshTools/algorithms/PointEdgeWave/PointData.H
@@ -48,8 +48,6 @@ namespace Foam
 {
 
 // Forward Declarations
-class Istream;
-class Ostream;
 template<class DataType> class PointData;
 
 template<class DataType>
diff --git a/src/meshTools/algorithms/PointEdgeWave/pointEdgePoint.H b/src/meshTools/algorithms/PointEdgeWave/pointEdgePoint.H
index 230a228a2e..9a267c6ddb 100644
--- a/src/meshTools/algorithms/PointEdgeWave/pointEdgePoint.H
+++ b/src/meshTools/algorithms/PointEdgeWave/pointEdgePoint.H
@@ -41,11 +41,10 @@ SourceFiles
 #ifndef Foam_pointEdgePoint_H
 #define Foam_pointEdgePoint_H
 
-#include "point.H"
 #include "label.H"
 #include "scalar.H"
+#include "point.H"
 #include "tensor.H"
-#include "pTraits.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
diff --git a/src/meshTools/edgeMesh/edgeMeshTools/edgeMeshTools.H b/src/meshTools/edgeMesh/edgeMeshTools/edgeMeshTools.H
index 04d9e1a127..237b084f43 100644
--- a/src/meshTools/edgeMesh/edgeMeshTools/edgeMeshTools.H
+++ b/src/meshTools/edgeMesh/edgeMeshTools/edgeMeshTools.H
@@ -35,8 +35,8 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef edgeMeshTools_H
-#define edgeMeshTools_H
+#ifndef Foam_edgeMeshTools_H
+#define Foam_edgeMeshTools_H
 
 #include "tmp.H"
 #include "scalarField.H"
@@ -46,12 +46,12 @@ SourceFiles
 namespace Foam
 {
 
+// Forward Declarations
 class edgeMesh;
 class extendedEdgeMesh;
 class extendedFeatureEdgeMesh;
 class triSurface;
 class Time;
-class Ostream;
 
 /*---------------------------------------------------------------------------*\
                       Namespace edgeMeshTools Declaration
diff --git a/src/phaseSystemModels/multiphaseInter/phasesSystem/MassTransferPhaseSystem/MassTransferPhaseSystem.C b/src/phaseSystemModels/multiphaseInter/phasesSystem/MassTransferPhaseSystem/MassTransferPhaseSystem.C
index df41e3555b..9bdd167d89 100644
--- a/src/phaseSystemModels/multiphaseInter/phasesSystem/MassTransferPhaseSystem/MassTransferPhaseSystem.C
+++ b/src/phaseSystemModels/multiphaseInter/phasesSystem/MassTransferPhaseSystem/MassTransferPhaseSystem.C
@@ -614,7 +614,7 @@ void Foam::MassTransferPhaseSystem<BasePhaseSystem>::alphaTransfer
             scalar dmdt21 = dmdtNet[celli];
             scalar coeffs12Cell = coeffs12[celli];
 
-            scalar alpha1Limited = clamp(alpha1[celli], 0, 1);
+            scalar alpha1Limited = clamp(alpha1[celli], zero_one{});
 
             // exp.
             SuPhase1[celli] += coeffs1[celli]*dmdt21;
@@ -657,7 +657,7 @@ void Foam::MassTransferPhaseSystem<BasePhaseSystem>::alphaTransfer
             scalar dmdt12 = -dmdtNet[celli];
             scalar coeffs21Cell = -coeffs12[celli];
 
-            scalar alpha2Limited = clamp(alpha2[celli], 0, 1);
+            scalar alpha2Limited = clamp(alpha2[celli], zero_one{});
 
             // exp
             SuPhase2[celli] += coeffs2[celli]*dmdt12;
diff --git a/src/rigidBodyDynamics/rigidBodyInertia/rigidBodyInertia.H b/src/rigidBodyDynamics/rigidBodyInertia/rigidBodyInertia.H
index 7c119b4b85..010f0f39ad 100644
--- a/src/rigidBodyDynamics/rigidBodyInertia/rigidBodyInertia.H
+++ b/src/rigidBodyDynamics/rigidBodyInertia/rigidBodyInertia.H
@@ -57,15 +57,10 @@ SourceFiles
 
 namespace Foam
 {
-
-// Forward declaration of classes
-class Istream;
-class Ostream;
-
 namespace RBD
 {
 
-// Forward declaration of friend functions and operators
+// Forward Declarations
 class rigidBodyInertia;
 Istream& operator>>(Istream&, rigidBodyInertia&);
 Ostream& operator<<(Ostream&, const rigidBodyInertia&);
diff --git a/src/rigidBodyDynamics/rigidBodyModelState/rigidBodyModelState.H b/src/rigidBodyDynamics/rigidBodyModelState/rigidBodyModelState.H
index 876ab85dfe..eb0b66f737 100644
--- a/src/rigidBodyDynamics/rigidBodyModelState/rigidBodyModelState.H
+++ b/src/rigidBodyDynamics/rigidBodyModelState/rigidBodyModelState.H
@@ -47,15 +47,10 @@ SourceFiles
 
 namespace Foam
 {
-
-// Forward declaration of classes
-class Istream;
-class Ostream;
-
 namespace RBD
 {
 
-// Forward declaration of friend functions and operators
+// Forward Declarations
 class rigidBodyModelState;
 Istream& operator>>(Istream&, rigidBodyModelState&);
 Ostream& operator<<(Ostream&, const rigidBodyModelState&);
diff --git a/src/sampling/surface/isoSurface/isoSurfaceParams.H b/src/sampling/surface/isoSurface/isoSurfaceParams.H
index df16e68a07..e371cd1f48 100644
--- a/src/sampling/surface/isoSurface/isoSurfaceParams.H
+++ b/src/sampling/surface/isoSurface/isoSurfaceParams.H
@@ -56,8 +56,8 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef isoSurfaceParams_H
-#define isoSurfaceParams_H
+#ifndef Foam_isoSurfaceParams_H
+#define Foam_isoSurfaceParams_H
 
 #include "boundBox.H"
 #include "Enum.H"
@@ -69,7 +69,6 @@ namespace Foam
 
 // Forward Declarations
 class dictionary;
-class Ostream;
 
 /*---------------------------------------------------------------------------*\
                      Class isoSurfaceSelector Declaration
diff --git a/src/sixDoFRigidBodyMotion/pointPatchFields/derived/sixDoFRigidBodyDisplacement/sixDoFRigidBodyDisplacementPointPatchVectorField.C b/src/sixDoFRigidBodyMotion/pointPatchFields/derived/sixDoFRigidBodyDisplacement/sixDoFRigidBodyDisplacementPointPatchVectorField.C
index ee455f158a..3ccf20ba72 100644
--- a/src/sixDoFRigidBodyMotion/pointPatchFields/derived/sixDoFRigidBodyDisplacement/sixDoFRigidBodyDisplacementPointPatchVectorField.C
+++ b/src/sixDoFRigidBodyMotion/pointPatchFields/derived/sixDoFRigidBodyDisplacement/sixDoFRigidBodyDisplacementPointPatchVectorField.C
@@ -233,7 +233,7 @@ void sixDoFRigidBodyDisplacementPointPatchVectorField::updateCoeffs()
         g_ = g.value();
     }
 
-    // scalar ramp = clamp((t.value() - 5)/10, 0, 1);
+    // scalar ramp = clamp((t.value() - 5)/10, zero_one{});
     scalar ramp = 1.0;
 
     motion_.update
diff --git a/src/sixDoFRigidBodyMotion/sixDoFRigidBodyMotion/sixDoFRigidBodyMotionState.H b/src/sixDoFRigidBodyMotion/sixDoFRigidBodyMotion/sixDoFRigidBodyMotionState.H
index 2194c43ec1..8889ed91cd 100644
--- a/src/sixDoFRigidBodyMotion/sixDoFRigidBodyMotion/sixDoFRigidBodyMotionState.H
+++ b/src/sixDoFRigidBodyMotion/sixDoFRigidBodyMotion/sixDoFRigidBodyMotionState.H
@@ -54,8 +54,6 @@ namespace Foam
 {
 
 // Forward Declarations
-class Istream;
-class Ostream;
 class sixDoFRigidBodyMotionState;
 Istream& operator>>(Istream&, sixDoFRigidBodyMotionState&);
 Ostream& operator<<(Ostream&, const sixDoFRigidBodyMotionState&);
diff --git a/src/surfMesh/MeshedSurface/MeshedSurface.H b/src/surfMesh/MeshedSurface/MeshedSurface.H
index 77f7da7c8f..87c7181ee6 100644
--- a/src/surfMesh/MeshedSurface/MeshedSurface.H
+++ b/src/surfMesh/MeshedSurface/MeshedSurface.H
@@ -76,8 +76,6 @@ namespace Foam
 class Time;
 class surfMesh;
 class polyBoundaryMesh;
-class Istream;
-class Ostream;
 
 template<class Face> class MeshedSurface;
 template<class Face> class MeshedSurfaceProxy;
diff --git a/src/surfMesh/UnsortedMeshedSurface/UnsortedMeshedSurface.H b/src/surfMesh/UnsortedMeshedSurface/UnsortedMeshedSurface.H
index 7834a4fb4f..951921cfaa 100644
--- a/src/surfMesh/UnsortedMeshedSurface/UnsortedMeshedSurface.H
+++ b/src/surfMesh/UnsortedMeshedSurface/UnsortedMeshedSurface.H
@@ -64,8 +64,6 @@ namespace Foam
 
 // Forward Declarations
 class Time;
-class Istream;
-class Ostream;
 
 template<class Face> class MeshedSurface;
 template<class Face> class MeshedSurfaceProxy;
diff --git a/src/waveModels/derivedPointPatchFields/waveMaker/waveMakerPointPatchVectorField.C b/src/waveModels/derivedPointPatchFields/waveMaker/waveMakerPointPatchVectorField.C
index c4168f0969..9db52d9592 100644
--- a/src/waveModels/derivedPointPatchFields/waveMaker/waveMakerPointPatchVectorField.C
+++ b/src/waveModels/derivedPointPatchFields/waveMaker/waveMakerPointPatchVectorField.C
@@ -89,7 +89,7 @@ Foam::scalar Foam::waveMakerPointPatchVectorField::timeCoeff
     const scalar t
 ) const
 {
-    return clamp(t/rampTime_, 0, 1);
+    return clamp(t/rampTime_, zero_one{});
 }
 
 
diff --git a/src/waveModels/waveGenerationModels/base/irregularWaveModel/irregularWaveModel.C b/src/waveModels/waveGenerationModels/base/irregularWaveModel/irregularWaveModel.C
index aac185602f..bfff32aef2 100644
--- a/src/waveModels/waveGenerationModels/base/irregularWaveModel/irregularWaveModel.C
+++ b/src/waveModels/waveGenerationModels/base/irregularWaveModel/irregularWaveModel.C
@@ -46,7 +46,7 @@ Foam::scalar Foam::waveModels::irregularWaveModel::timeCoeff
     const scalar t
 ) const
 {
-    return clamp(t/rampTime_, 0, 1);
+    return clamp(t/rampTime_, zero_one{});
 }