ENH: align zones writing pattern with polyBoundaryMesh, patchField etc.

STYLE: output the zone meta data (names) as an undecorated wordList

ENH: extra safety check in reorderZones to avoid any possible leaking

applications/utilities/mesh/generation/blockMesh/mergePatchPairs.H

@@ -152,7 +152,7 @@ Description
 
                 if
                 (
-                    !cleanupPatches.found(patchName)
+                    !cleanupPatches.contains(patchName)
                  || returnReduceOr(oldPatches[patchi].size())
                 )
                 {
@@ -188,8 +188,9 @@ Description
 
         // Cleanup empty merged point zones
         {
-            PtrList<pointZone>& zones = mesh.pointZones();
+            auto& zmesh = mesh.pointZones();
-            mesh.pointZones().clearAddressing();
+            zmesh.clearAddressing();
+            PtrList<pointZone>& zones = zmesh;
 
             wordHashSet removedZones(2*zones.size());
 
@@ -198,12 +199,11 @@ Description
             {
                 if
                 (
-                    !cleanupPointZones.found(zones[zonei].name())
+                    !cleanupPointZones.contains(zones[zonei].name())
                  || returnReduceOr(zones[zonei].size())
                 )
                 {
                     zones.set(nZones, zones.release(zonei));
-                    zones[nZones].index() = nZones;  // re-index
                     ++nZones;
                 }
                 else
@@ -212,6 +212,7 @@ Description
                 }
             }
             zones.resize(nZones);
+            zmesh.reindex();
 
             if (removedZones.size())
             {
@@ -223,8 +224,9 @@ Description
 
         // Cleanup empty merged face zones
         {
-            PtrList<faceZone>& zones = mesh.faceZones();
+            auto& zmesh = mesh.faceZones();
-            mesh.faceZones().clearAddressing();
+            zmesh.clearAddressing();
+            PtrList<faceZone>& zones = zmesh;
 
             wordHashSet removedZones(2*zones.size());
 
@@ -233,12 +235,11 @@ Description
             {
                 if
                 (
-                    !cleanupFaceZones.found(zones[zonei].name())
+                    !cleanupFaceZones.contains(zones[zonei].name())
                  || returnReduceOr(zones[zonei].size())
                 )
                 {
                     zones.set(nZones, zones.release(zonei));
-                    zones[nZones].index() = nZones;  // re-index
                     ++nZones;
                 }
                 else
@@ -247,6 +248,7 @@ Description
                 }
             }
             zones.resize(nZones);
+            zmesh.reindex();
 
             if (removedZones.size())
             {

src/OpenFOAM/meshes/Identifiers/patch/patchIdentifier.C

@@ -33,7 +33,6 @@ License
 
 Foam::patchIdentifier::patchIdentifier()
 :
-    name_(),
     index_(0)
 {}
 

src/OpenFOAM/meshes/Identifiers/surface/geometricSurfacePatch.C

@@ -33,15 +33,15 @@ License
 
 Foam::geometricSurfacePatch::geometricSurfacePatch()
 :
-    geometricSurfacePatch(0)
+    name_("patch"),
+    index_(0)
 {}
 
 
 Foam::geometricSurfacePatch::geometricSurfacePatch(const label index)
 :
     name_("patch"),
-    index_(index),
+    index_(index)
-    geometricType_()
 {}
 
 
@@ -52,8 +52,7 @@ Foam::geometricSurfacePatch::geometricSurfacePatch
 )
 :
     name_(name),
-    index_(index),
+    index_(index)
-    geometricType_()
 {}
 
 

src/OpenFOAM/meshes/Identifiers/surface/geometricSurfacePatch.H

@@ -36,8 +36,8 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef geometricSurfacePatch_H
+#ifndef Foam_geometricSurfacePatch_H
-#define geometricSurfacePatch_H
+#define Foam_geometricSurfacePatch_H
 
 #include "surfZoneIdentifier.H"
 #include "stdFoam.H"
@@ -106,9 +106,16 @@ public:
         //- Copy construct
         geometricSurfacePatch(const geometricSurfacePatch&) = default;
 
+        //- Move construct
+        geometricSurfacePatch(geometricSurfacePatch&&) = default;
+
         //- Copy assignment
         geometricSurfacePatch&
-            operator=(const geometricSurfacePatch&) = default;
+        operator=(const geometricSurfacePatch&) = default;
+
+        //- Move assignment
+        geometricSurfacePatch&
+        operator=(geometricSurfacePatch&&) = default;
 
 
     // Constructors
@@ -147,40 +154,22 @@ public:
     // Member Functions
 
         //- The patch/zone name
-        const word& name() const noexcept
+        const word& name() const noexcept { return name_; }
-        {
-            return name_;
-        }
 
         //- Modifiable patch/zone name
-        word& name() noexcept
+        word& name() noexcept { return name_; }
-        {
-            return name_;
-        }
 
         //- The index of this patch/zone in the surface mesh
-        label index() const noexcept
+        label index() const noexcept { return index_; }
-        {
-            return index_;
-        }
 
         //- Modifiable index of this patch/zone in the surface mesh
-        label& index() noexcept
+        label& index() noexcept { return index_; }
-        {
-            return index_;
-        }
 
         //- The geometric type of the patch/zone
-        const word& geometricType() const noexcept
+        const word& geometricType() const noexcept { return geometricType_; }
-        {
-            return geometricType_;
-        }
 
         //- Modifiable geometric type of the patch/zone
-        word& geometricType() noexcept
+        word& geometricType() noexcept { return geometricType_; }
-        {
-            return geometricType_;
-        }
 
         //- Write (geometricType) dictionary entry
         //- (without surrounding braces)

src/OpenFOAM/meshes/Identifiers/surface/surfZoneIdentifier.C

@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011 OpenFOAM Foundation
-    Copyright (C) 2016-2021 OpenCFD Ltd.
+    Copyright (C) 2016-2025 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -33,15 +33,13 @@ License
 
 Foam::surfZoneIdentifier::surfZoneIdentifier()
 :
-    surfZoneIdentifier(0)
+    index_(0)
 {}
 
 
 Foam::surfZoneIdentifier::surfZoneIdentifier(const label index)
 :
-    name_(),
+    index_(index)
-    index_(index),
-    geometricType_()
 {}
 
 
@@ -52,8 +50,7 @@ Foam::surfZoneIdentifier::surfZoneIdentifier
 )
 :
     name_(name),
-    index_(index),
+    index_(index)
-    geometricType_()
 {}
 
 
@@ -77,9 +74,7 @@ Foam::surfZoneIdentifier::surfZoneIdentifier
     const label index
 )
 :
-    name_(name),
+    surfZoneIdentifier(name, index)
-    index_(index),
-    geometricType_()
 {
     dict.readIfPresent("geometricType", geometricType_);
 }
@@ -88,13 +83,31 @@ Foam::surfZoneIdentifier::surfZoneIdentifier
 Foam::surfZoneIdentifier::surfZoneIdentifier
 (
     const surfZoneIdentifier& ident,
-    const label index
+    const label newIndex
 )
 :
-    name_(ident.name_),
+    surfZoneIdentifier(ident)
-    index_(index),
+{
-    geometricType_(ident.geometricType_)
+    if (newIndex >= 0)
-{}
+    {
+        index_ = newIndex;
+    }
+}
+
+
+Foam::surfZoneIdentifier::surfZoneIdentifier
+(
+    surfZoneIdentifier&& ident,
+    const label newIndex
+)
+:
+    surfZoneIdentifier(std::move(ident))
+{
+    if (newIndex >= 0)
+    {
+        index_ = newIndex;
+    }
+}
 
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //

src/OpenFOAM/meshes/Identifiers/surface/surfZoneIdentifier.H

@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011 OpenFOAM Foundation
-    Copyright (C) 2016-2021 OpenCFD Ltd.
+    Copyright (C) 2016-2025 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -39,8 +39,8 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef surfZoneIdentifier_H
+#ifndef Foam_surfZoneIdentifier_H
-#define surfZoneIdentifier_H
+#define Foam_surfZoneIdentifier_H
 
 #include "word.H"
 #include "label.H"
@@ -97,16 +97,22 @@ public:
         //- Copy construct
         surfZoneIdentifier(const surfZoneIdentifier&) = default;
 
+        //- Move construct
+        surfZoneIdentifier(surfZoneIdentifier&&) = default;
+
         //- Copy assignment
         surfZoneIdentifier& operator=(const surfZoneIdentifier&) = default;
 
+        //- Move assignment
+        surfZoneIdentifier& operator=(surfZoneIdentifier&&) = default;
+
 
     // Constructors
 
         //- Default construct. Uses name="", index=0
         surfZoneIdentifier();
 
-        //- Construct null with specified index
+        //- Construct with name="" and specified index
         explicit surfZoneIdentifier(const label index);
 
         //- Construct from mandatory components
@@ -128,51 +134,40 @@ public:
             const label index
         );
 
-        //- Copy construct, resetting the index
+        //- Copy construct, resetting the index (if non-negative)
         surfZoneIdentifier
         (
             const surfZoneIdentifier& ident,
-            const label index
+            const label newIndex
+        );
+
+        //- Move construct, resetting the index (if non-negative)
+        surfZoneIdentifier
+        (
+            surfZoneIdentifier&& ident,
+            const label newIndex
         );
 
 
     // Member Functions
 
         //- The patch/zone name
-        const word& name() const
+        const word& name() const noexcept { return name_; }
-        {
-            return name_;
-        }
 
         //- Modifiable patch/zone name
-        word& name()
+        word& name() noexcept { return name_; }
-        {
-            return name_;
-        }
 
-        //- The geometric type of the patch/zone
+        //- The (optional) geometric type of the patch/zone
-        const word& geometricType() const
+        const word& geometricType() const noexcept { return geometricType_; }
-        {
-            return geometricType_;
-        }
 
-        //- Modifiable geometric type of the patch/zone
+        //- Modifiable (optional) geometric type of the patch/zone
-        word& geometricType()
+        word& geometricType() noexcept { return geometricType_; }
-        {
-            return geometricType_;
-        }
 
         //- The index of this patch/zone in the surface mesh
-        label index() const
+        label index() const noexcept { return index_; }
-        {
-            return index_;
-        }
 
         //- Modifiable index of this patch/zone in the surface mesh
-        label& index()
+        label& index() noexcept { return index_; }
-        {
-            return index_;
-        }
 
         //- Write (geometricType) dictionary entry
         //- (without surrounding braces)

src/OpenFOAM/meshes/Identifiers/zone/zoneIdentifier.C

@@ -32,7 +32,6 @@ License
 
 Foam::zoneIdentifier::zoneIdentifier()
 :
-    name_(),
     index_(0)
 {}
 

src/OpenFOAM/meshes/polyMesh/polyBoundaryMesh/polyBoundaryMesh.C

@@ -1506,7 +1506,10 @@ void Foam::polyBoundaryMesh::writeEntry
     if (!keyword.empty())
     {
         os.write(keyword);
-        os << (entries.empty() ? token::SPACE : token::NL);
+        if (entries.empty())
+        {
+            os << token::SPACE;
+        }
     }
 
     writeEntry(os);

src/OpenFOAM/meshes/polyMesh/zones/ZoneMesh/ZoneMesh.C

@@ -530,6 +530,32 @@ const
 }
 
 
+template<class ZoneType, class MeshType>
+bool Foam::ZoneMesh<ZoneType, MeshType>::reindex()
+{
+    PtrList<ZoneType>& zones = *this;
+
+    bool changed = false;
+
+    // Adapt indices
+    forAll(zones, zonei)
+    {
+        if (zones[zonei].index() != zonei)
+        {
+            zones[zonei].index() = zonei;
+            changed = true;
+        }
+    }
+
+    if (changed)
+    {
+        this->clearLocalAddressing();
+    }
+
+    return changed;
+}
+
+
 template<class ZoneType, class MeshType>
 Foam::labelList Foam::ZoneMesh<ZoneType, MeshType>::indices
 (
@@ -1069,16 +1095,76 @@ void Foam::ZoneMesh<ZoneType, MeshType>::updateMetaData()
     }
     else
     {
-        dictionary& meta = this->getMetaData();
+        // Save as a list of names without the leading size
-        meta.set("names", zoneNames);
+        tokenList toks(2+zoneNames.size());
+
+        auto iter = toks.begin();
+        (*iter).pToken(token::BEGIN_LIST);
+        iter = std::move(zoneNames.begin(), zoneNames.end(), ++iter);
+        (*iter).pToken(token::END_LIST);
+
+        this->getMetaData().set("names", std::move(toks));
     }
 }
 
 
+// * * * * * * * * * * * * * * * IOstream Operators  * * * * * * * * * * * * //
+
+template<class ZoneType, class MeshType>
+void Foam::ZoneMesh<ZoneType, MeshType>::writeEntry(Ostream& os) const
+{
+    const PtrList<ZoneType>& entries = *this;
+
+    os << entries.size();
+
+    if (entries.empty())
+    {
+        // 0-sized : can write with less vertical space
+        os << token::BEGIN_LIST << token::END_LIST;
+    }
+    else
+    {
+        os << nl << token::BEGIN_LIST << nl;
+
+        for (const auto& zn : entries)
+        {
+            os.beginBlock(zn.name());
+            zn.write(os);
+            os.endBlock();
+        }
+        os << token::END_LIST;
+    }
+}
+
+
+template<class ZoneType, class MeshType>
+void Foam::ZoneMesh<ZoneType, MeshType>::writeEntry
+(
+    const word& keyword,
+    Ostream& os
+) const
+{
+    const PtrList<ZoneType>& entries = *this;
+
+    if (!keyword.empty())
+    {
+        os.write(keyword);
+        if (entries.empty())
+        {
+            os << token::SPACE;
+        }
+    }
+
+    writeEntry(os);
+
+    if (!keyword.empty()) os.endEntry();
+}
+
+
 template<class ZoneType, class MeshType>
 bool Foam::ZoneMesh<ZoneType, MeshType>::writeData(Ostream& os) const
 {
-    os  << *this;
+    writeEntry(os);
     return os.good();
 }
 
@@ -1163,24 +1249,7 @@ Foam::Ostream& Foam::operator<<
     const ZoneMesh<ZoneType, MeshType>& zones
 )
 {
-    const label sz = zones.size();
+    zones.writeEntry(os);
-
-    if (sz)
-    {
-        os  << sz << nl << token::BEGIN_LIST;
-
-        for (label i=0; i < sz; ++i)
-        {
-            zones[i].writeDict(os);
-        }
-
-        os  << token::END_LIST;
-    }
-    else
-    {
-        os  << sz << token::BEGIN_LIST << token::END_LIST;
-    }
-
     return os;
 }
 

src/OpenFOAM/meshes/polyMesh/zones/ZoneMesh/ZoneMesh.H

@@ -113,6 +113,9 @@ public:
 
     // Public Typedefs
 
+        //- The referenced mesh type
+        typedef MeshType mesh_type;
+
         //- The zone type. Same as PtrList<ZoneType>::value_type
         typedef ZoneType zone_type;
 
@@ -226,6 +229,11 @@ public:
         //- Sorted list of zone names satisfying the input matchers
         wordList sortedNames(const wordRes& matcher) const;
 
+        //- Adjust the index of zone entries to be consistent with their
+        //- position in the list.
+        //  If the indexing changed, invalidates any mapping.
+        //  \returns true if the indexing changed.
+        bool reindex();
 
         //- The (sorted) patch indices for all matches,
         //- optionally matching zone groups.
@@ -380,8 +388,15 @@ public:
         //- Update internal meta-data (eg, prior to writing)
         void updateMetaData();
 
+        //- Write as a plain list of entries
+        void writeEntry(Ostream& os) const;
+
+        //- Write as a primitive entry with given name.
+        //- If the keyword is empty, revert to a plain list.
+        void writeEntry(const word& keyword, Ostream& os) const;
+
         //- The writeData member function required by regIOobject
-        bool writeData(Ostream& os) const;
+        virtual bool writeData(Ostream& os) const;
 
 
     // Ostream Operator

src/OpenFOAM/meshes/polyMesh/zones/cellZone/cellZone.C

@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011 OpenFOAM Foundation
-    Copyright (C) 2017-2023 OpenCFD Ltd.
+    Copyright (C) 2017-2025 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -27,11 +27,10 @@ License
 \*---------------------------------------------------------------------------*/
 
 #include "cellZone.H"
-#include "addToRunTimeSelectionTable.H"
 #include "cellZoneMesh.H"
 #include "polyMesh.H"
-#include "primitiveMesh.H"
 #include "IOstream.H"
+#include "addToRunTimeSelectionTable.H"
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
@@ -42,14 +41,12 @@ namespace Foam
     addToRunTimeSelectionTable(cellZone, cellZone, dictionary);
 }
 
-const char * const Foam::cellZone::labelsName = "cellLabels";
-
-
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
 Foam::cellZone::cellZone(const cellZoneMesh& zm)
 :
-    cellZone(word::null, 0, zm)
+    zone(),
+    zoneMesh_(zm)
 {}
 
 
@@ -99,7 +96,7 @@ Foam::cellZone::cellZone
     const cellZoneMesh& zm
 )
 :
-    zone(name, dict, this->labelsName, index),
+    zone(name, dict, cellZone::labelsName(), index),
     zoneMesh_(zm)
 {}
 
@@ -107,7 +104,19 @@ Foam::cellZone::cellZone
 Foam::cellZone::cellZone
 (
     const cellZone& originalZone,
-    const Foam::zero,
+    const cellZoneMesh& zm,
+    const label newIndex
+)
+:
+    zone(originalZone, newIndex),
+    zoneMesh_(zm)
+{}
+
+
+Foam::cellZone::cellZone
+(
+    const cellZone& originalZone,
+    Foam::zero,
     const cellZoneMesh& zm,
     const label newIndex
 )
@@ -120,7 +129,7 @@ Foam::cellZone::cellZone
 Foam::cellZone::cellZone
 (
     const cellZone& originalZone,
-    const Foam::zero,
+    Foam::zero,
     const label index,
     const cellZoneMesh& zm
 )
@@ -160,28 +169,17 @@ Foam::cellZone::cellZone
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
-Foam::label Foam::cellZone::whichCell(const label globalCellID) const
+Foam::label Foam::cellZone::max_index() const noexcept
 {
-    return zone::localID(globalCellID);
+    return zoneMesh_.mesh().nCells();
 }
 
 
-bool Foam::cellZone::checkDefinition(const bool report) const
+// void Foam::cellZone::sort()
-{
+// {
-    return zone::checkDefinition(zoneMesh_.mesh().nCells(), report);
+//     clearAddressing();
-}
+//     Foam::sort(static_cast<labelList&>(*this));
-
+// }
-
-void Foam::cellZone::writeDict(Ostream& os) const
-{
-    os.beginBlock(name());
-
-    os.writeEntry("type", type());
-    zoneIdentifier::write(os);
-    writeEntry(this->labelsName, os);
-
-    os.endBlock();
-}
 
 
 void Foam::cellZone::resetAddressing(cellZone&& zn)
@@ -223,6 +221,13 @@ void Foam::cellZone::resetAddressing(labelList&& addr)
 }
 
 
+void Foam::cellZone::write(Ostream& os) const
+{
+    zone::write(os);
+    labelList::writeEntry(cellZone::labelsName(), os);
+}
+
+
 // * * * * * * * * * * * * * * * Member Operators  * * * * * * * * * * * * * //
 
 void Foam::cellZone::operator=(const cellZone& zn)

src/OpenFOAM/meshes/polyMesh/zones/cellZone/cellZone.H

@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2017-2023 OpenCFD Ltd.
+    Copyright (C) 2017-2025 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -75,8 +75,7 @@ public:
     // Static Data Members
 
         //- The name associated with the zone-labels dictionary entry
-        //- ("cellLabels")
+        static constexpr const char* labelsName() { return "cellLabels"; }
-        static const char * const labelsName;
 
 
     //- Runtime type information
@@ -143,13 +142,23 @@ public:
             const cellZoneMesh& zm
         );
 
-        //- Construct empty with original zone information (name, index, groups)
+        //- Copy construct with new mesh reference.
-        //- and mesh reference. Optionally specify a new index.
         cellZone
         (
             const cellZone& originalZone,
-            const Foam::zero,
             const cellZoneMesh& zm,
+            //! The new index (optional. -1 retains the original value)
+            const label newIndex = -1
+        );
+
+        //- Construct empty with original zone information (name, index, groups)
+        //- and mesh reference.
+        cellZone
+        (
+            const cellZone& originalZone,
+            Foam::zero,
+            const cellZoneMesh& zm,
+            //! The new index (optional. -1 retains the original value)
             const label newIndex = -1
         );
 
@@ -158,7 +167,8 @@ public:
         cellZone
         (
             const cellZone& originalZone,
-            const Foam::zero,
+            Foam::zero,
+            //! The new index (-1 retains the original value)
             const label index,
             const cellZoneMesh& zm
         );
@@ -169,6 +179,7 @@ public:
         (
             const cellZone& originalZone,
             const labelUList& addr,
+            //! The new index (-1 retains the original value)
             const label index,
             const cellZoneMesh& zm
         );
@@ -179,15 +190,21 @@ public:
         (
             const cellZone& originalZone,
             labelList&& addr,
+            //! The new index (-1 retains the original value)
             const label index,
             const cellZoneMesh& zm
         );
 
 
         //- Construct and return a clone, resetting the zone mesh
-        virtual autoPtr<cellZone> clone(const cellZoneMesh& zm) const
+        virtual autoPtr<cellZone> clone
+        (
+            const cellZoneMesh& zm,
+            //! The new index (optional. -1 retains the original value)
+            const label newIndex = -1
+        ) const
         {
-            return autoPtr<cellZone>::New(*this, *this, index(), zm);
+            return autoPtr<cellZone>::New(*this, zm, newIndex);
         }
 
         //- Construct and return a clone,
@@ -195,6 +212,7 @@ public:
         virtual autoPtr<cellZone> clone
         (
             const labelUList& addr,
+            //! The new index (-1 retains the original value)
             const label index,
             const cellZoneMesh& zm
         ) const
@@ -222,21 +240,30 @@ public:
 
     // Member Functions
 
+        //- The maximum index the zone may contain == mesh nCells()
+        label max_index() const noexcept;
+
         //- Return reference to the zone mesh
         const cellZoneMesh& zoneMesh() const noexcept { return zoneMesh_; }
 
         //- The addressing (cell IDs) used for the zone
-        const labelList& addressing() const noexcept
+        using zone::addressing;
+
+        //- The local index of the given mesh cell, -1 if not in the zone
+        label whichCell(const label meshCellID) const
         {
-            return static_cast<const labelList&>(*this);
+            return zone::localID(meshCellID);
         }
 
-        //- Helper function to re-direct to zone::localID(...)
-        label whichCell(const label globalCellID) const;
 
+    // Checks
 
-        //- Check zone definition. Return true if in error.
+        //- Check zone definition.
-        virtual bool checkDefinition(const bool report = false) const;
+        //  \return True if any errors.
+        virtual bool checkDefinition(const bool report = false) const
+        {
+            return zone::checkDefinition(max_index(), report);
+        }
 
         //- Check whether zone is synchronised across coupled boundaries.
         //  \return True if any errors.
@@ -245,9 +272,6 @@ public:
             return false;
         }
 
-        //- Write dictionary
-        virtual void writeDict(Ostream& os) const;
-
 
     // Assign addressing
 
@@ -275,8 +299,22 @@ public:
 
     // I-O
 
+        //- Write (dictionary entries)
+        virtual void write(Ostream& os) const;
+
         //- Ostream Operator
         friend Ostream& operator<<(Ostream& os, const cellZone& zn);
+
+
+    // Housekeeping
+
+        //- Deprecated(2025-09) Write dictionary
+        //  \deprecated(2025-09) Write dictionary
+        FOAM_DEPRECATED_FOR(2025-09, "write() or operator<<")
+        void writeDict(Ostream& os) const
+        {
+            os.beginBlock(name()); write(os); os.endBlock();
+        }
 };
 
 

src/OpenFOAM/meshes/polyMesh/zones/cellZone/cellZoneMeshFwd.H

@@ -41,7 +41,7 @@ namespace Foam
     class cellZone;
     class polyMesh;
 
-    template<class Zone, class MeshType> class ZoneMesh;
+    template<class ZoneType, class MeshType> class ZoneMesh;
     typedef ZoneMesh<cellZone, polyMesh> cellZoneMesh;
 }
 

src/OpenFOAM/meshes/polyMesh/zones/faceZone/faceZone.C

@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2017-2023 OpenCFD Ltd.
+    Copyright (C) 2017-2025 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -27,12 +27,11 @@ License
 \*---------------------------------------------------------------------------*/
 
 #include "faceZone.H"
-#include "addToRunTimeSelectionTable.H"
 #include "faceZoneMesh.H"
 #include "polyMesh.H"
-#include "primitiveMesh.H"
 #include "mapPolyMesh.H"
 #include "syncTools.H"
+#include "addToRunTimeSelectionTable.H"
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
@@ -43,8 +42,6 @@ namespace Foam
     addToRunTimeSelectionTable(faceZone, faceZone, dictionary);
 }
 
-const char* const Foam::faceZone::labelsName = "faceLabels";
-
 
 // * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
 
@@ -220,7 +217,8 @@ void Foam::faceZone::checkAddressing() const
 
 Foam::faceZone::faceZone(const faceZoneMesh& zm)
 :
-    faceZone(word::null, 0, zm)
+    zone(),
+    zoneMesh_(zm)
 {}
 
 
@@ -329,10 +327,10 @@ Foam::faceZone::faceZone
     const faceZoneMesh& zm
 )
 :
-    zone(name, dict, this->labelsName, index),
+    zone(name, dict, faceZone::labelsName(), index),
-    flipMap_(dict.lookup("flipMap")),  // OR: dict.get<boolList>("flipMap")
     zoneMesh_(zm)
 {
+    dict.readEntry("flipMap", flipMap_, keyType::LITERAL);
     checkAddressing();
 }
 
@@ -340,7 +338,21 @@ Foam::faceZone::faceZone
 Foam::faceZone::faceZone
 (
     const faceZone& originalZone,
-    const Foam::zero,
+    const faceZoneMesh& zm,
+    const label newIndex
+)
+:
+    zone(originalZone, newIndex),
+    zoneMesh_(zm)
+{
+    flipMap_ = originalZone.flipMap();
+}
+
+
+Foam::faceZone::faceZone
+(
+    const faceZone& originalZone,
+    Foam::zero,
     const faceZoneMesh& zm,
     const label newIndex
 )
@@ -353,7 +365,7 @@ Foam::faceZone::faceZone
 Foam::faceZone::faceZone
 (
     const faceZone& originalZone,
-    const Foam::zero,
+    Foam::zero,
     const label index,
     const faceZoneMesh& zm
 )
@@ -401,12 +413,23 @@ Foam::faceZone::faceZone
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
-Foam::label Foam::faceZone::whichFace(const label globalFaceID) const
+Foam::label Foam::faceZone::max_index() const noexcept
 {
-    return zone::localID(globalFaceID);
+    return zoneMesh_.mesh().nFaces();
 }
 
 
+// void Foam::faceZone::sort()
+// {
+//    clearAddressing();
+//    auto& addr = static_cast<labelList&>(*this);
+//
+//    auto order = Foam::sortedOrder(addr);
+//    addr = labelList(addr, order);
+//    flipMap_ = boolList(flipMap_, order);
+// }
+
+
 const Foam::primitiveFacePatch& Foam::faceZone::patch() const
 {
     if (!patchPtr_)
@@ -483,7 +506,6 @@ void Foam::faceZone::clearPrimitives()
 
 void Foam::faceZone::resetAddressing(faceZone&& zn)
 {
-    // TDB: clearGeom();
     if (this == &zn)
     {
         return;  // Self-assignment is a no-op
@@ -498,7 +520,6 @@ void Foam::faceZone::resetAddressing(faceZone&& zn)
 
 void Foam::faceZone::resetAddressing(const faceZone& zn)
 {
-    // TDB: clearGeom();
     if (this == &zn)
     {
         return;  // Self-assignment is a no-op
@@ -578,12 +599,6 @@ void Foam::faceZone::updateMesh(const mapPolyMesh& mpm)
 }
 
 
-bool Foam::faceZone::checkDefinition(const bool report) const
-{
-    return zone::checkDefinition(zoneMesh().mesh().faces().size(), report);
-}
-
-
 bool Foam::faceZone::checkParallelSync(const bool report) const
 {
     const polyMesh& mesh = zoneMesh().mesh();
@@ -683,24 +698,12 @@ void Foam::faceZone::movePoints(const pointField& pts)
     }
 }
 
+
 void Foam::faceZone::write(Ostream& os) const
 {
-    os  << nl << name()
+    zone::write(os);
-        << nl << static_cast<const labelList&>(*this)
+    labelList::writeEntry(faceZone::labelsName(), os);
-        << nl << flipMap();
+    flipMap_.writeEntry("flipMap", os);
-}
-
-
-void Foam::faceZone::writeDict(Ostream& os) const
-{
-    os.beginBlock(name());
-
-    os.writeEntry("type", type());
-    zoneIdentifier::write(os);
-    writeEntry(this->labelsName, os);
-    flipMap().writeEntry("flipMap", os);
-
-    os.endBlock();
 }
 
 

src/OpenFOAM/meshes/polyMesh/zones/faceZone/faceZone.H

@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2017-2023 OpenCFD Ltd.
+    Copyright (C) 2017-2025 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -78,13 +78,13 @@ class faceZone
 
     // Private Data
 
+        //- Reference to zone list
+        const faceZoneMesh& zoneMesh_;
+
         //- Flip map for all faces in the zone.
         //  True if the face needs flipping for the correct orientation.
         boolList flipMap_;
 
-        //- Reference to zone list
-        const faceZoneMesh& zoneMesh_;
-
         //- Demand-driven: Primitive patch of correctly flipped faces
         mutable std::unique_ptr<primitiveFacePatch> patchPtr_;
 
@@ -120,8 +120,7 @@ public:
     // Static Data Members
 
         //- The name associated with the zone-labels dictionary entry
-        //- ("faceLabels")
+        static constexpr const char* labelsName() { return "faceLabels"; }
-        static const char * const labelsName;
 
 
     //- Runtime type information
@@ -211,13 +210,23 @@ public:
             const faceZoneMesh& zm
         );
 
-        //- Construct empty with original zone information (name, index, groups)
+        //- Copy construct with new mesh reference.
-        //- and mesh reference. Optionally specify a new index.
         faceZone
         (
             const faceZone& originalZone,
-            const Foam::zero,
             const faceZoneMesh& zm,
+            //! The new index (optional. -1 retains the original value)
+            const label newIndex = -1
+        );
+
+        //- Construct empty with original zone information (name, index, groups)
+        //- and mesh reference.
+        faceZone
+        (
+            const faceZone& originalZone,
+            Foam::zero,
+            const faceZoneMesh& zm,
+            //! The new index (optional. -1 retains the original value)
             const label newIndex = -1
         );
 
@@ -226,7 +235,8 @@ public:
         faceZone
         (
             const faceZone& originalZone,
-            const Foam::zero,
+            Foam::zero,
+            //! The new index (-1 retains the original value)
             const label index,
             const faceZoneMesh& zm
         );
@@ -239,6 +249,7 @@ public:
             const faceZone& originalZone,
             const labelUList& addr,
             const boolUList& fm,
+            //! The new index (-1 retains the original value)
             const label index,
             const faceZoneMesh& zm
         );
@@ -251,14 +262,20 @@ public:
             const faceZone& originalZone,
             labelList&& addr,
             boolList&& fm,
+            //! The new index (-1 retains the original value)
             const label index,
             const faceZoneMesh& zm
         );
 
         //- Construct and return a clone, resetting the zone mesh
-        virtual autoPtr<faceZone> clone(const faceZoneMesh& zm) const
+        virtual autoPtr<faceZone> clone
+        (
+            const faceZoneMesh& zm,
+            //! The new index (optional. -1 retains the original value)
+            const label newIndex = -1
+        ) const
         {
-            return autoPtr<faceZone>::New(*this, *this, flipMap(), index(), zm);
+            return autoPtr<faceZone>::New(*this, zm, newIndex);
         }
 
         //- Construct and return a clone,
@@ -267,6 +284,7 @@ public:
         (
             const labelUList& addr,
             const boolUList& fm,
+            //! The new index (-1 retains the original value)
             const label index,
             const faceZoneMesh& zm
         ) const
@@ -294,26 +312,43 @@ public:
 
     // Member Functions
 
+        //- The maximum index the zone may contain == mesh nFaces()
+        label max_index() const noexcept;
+
         //- Return reference to the zone mesh
         const faceZoneMesh& zoneMesh() const noexcept { return zoneMesh_; }
 
         //- The addressing (face IDs) used for the zone
-        const labelList& addressing() const noexcept
+        using zone::addressing;
-        {
-            return static_cast<const labelList&>(*this);
-        }
 
         //- Return face flip map
         const boolList& flipMap() const noexcept { return flipMap_; }
 
-        //- Helper function to re-direct to zone::localID(...)
+        //- The local index of the given mesh face, -1 if not in the zone
-        label whichFace(const label globalCellID) const;
+        label whichFace(const label meshFaceID) const
+        {
+            return zone::localID(meshFaceID);
+        }
 
         //- Return [demand-driven] reference to an equivalent primitive patch,
         //- with faces oriented according to flipMap()
         const primitiveFacePatch& patch() const;
 
 
+    // Checks
+
+        //- Check zone definition.
+        //  \return True if any errors.
+        virtual bool checkDefinition(const bool report = false) const
+        {
+            return zone::checkDefinition(max_index(), report);
+        }
+
+        //- Check whether all procs have faces synchronised.
+        //  \return True if any errors.
+        virtual bool checkParallelSync(const bool report = false) const;
+
+
     // Addressing into mesh
 
         //- The front cells layer.
@@ -329,25 +364,6 @@ public:
         //- Return global edge index for local edges
         const labelList& meshEdges() const;
 
-        //- Check zone definition. Return true if in error.
-        virtual bool checkDefinition(const bool report = false) const;
-
-        //- Check whether all procs have faces synchronised.
-        //  \return True if any errors.
-        virtual bool checkParallelSync(const bool report = false) const;
-
-        //- Correct patch after moving points
-        virtual void movePoints(const pointField& pts);
-
-        //- Update for changes in topology
-        virtual void updateMesh(const mapPolyMesh& mpm);
-
-        //- Write
-        virtual void write(Ostream& os) const;
-
-        //- Write dictionary
-        virtual void writeDict(Ostream& os) const;
-
 
     // Assign addressing
 
@@ -392,8 +408,20 @@ public:
         void operator=(const faceZone& zn);
 
 
+    // Mesh Changes
+
+        //- Correct patch after moving points
+        virtual void movePoints(const pointField& pts);
+
+        //- Update for changes in topology
+        virtual void updateMesh(const mapPolyMesh& mpm);
+
+
     // I-O
 
+        //- Write (dictionary entries)
+        virtual void write(Ostream& os) const;
+
         //- Ostream Operator
         friend Ostream& operator<<(Ostream& os, const faceZone& zn);
 
@@ -411,6 +439,14 @@ public:
         //- Deprecated(2023-09) same as backCells
         //  \deprecated(2023-09) same as backCells #1832
         const labelList& slaveCells() const { return backCells(); }
+
+        //- Deprecated(2025-09) Write dictionary
+        //  \deprecated(2025-09) Write dictionary
+        FOAM_DEPRECATED_FOR(2025-09, "write() or operator<<")
+        void writeDict(Ostream& os) const
+        {
+            os.beginBlock(name()); write(os); os.endBlock();
+        }
 };
 
 

src/OpenFOAM/meshes/polyMesh/zones/faceZone/faceZoneMeshFwd.H

@@ -41,7 +41,7 @@ namespace Foam
     class faceZone;
     class polyMesh;
 
-    template<class Zone, class MeshType> class ZoneMesh;
+    template<class ZoneType, class MeshType> class ZoneMesh;
     typedef ZoneMesh<faceZone, polyMesh> faceZoneMesh;
 }
 

src/OpenFOAM/meshes/polyMesh/zones/pointZone/pointZone.C

@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2017-2023 OpenCFD Ltd.
+    Copyright (C) 2017-2025 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -27,11 +27,10 @@ License
 \*---------------------------------------------------------------------------*/
 
 #include "pointZone.H"
-#include "addToRunTimeSelectionTable.H"
 #include "pointZoneMesh.H"
 #include "polyMesh.H"
-#include "primitiveMesh.H"
 #include "syncTools.H"
+#include "addToRunTimeSelectionTable.H"
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
@@ -42,14 +41,13 @@ namespace Foam
     addToRunTimeSelectionTable(pointZone, pointZone, dictionary);
 }
 
-const char* const Foam::pointZone::labelsName = "pointLabels";
-
 
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
 Foam::pointZone::pointZone(const pointZoneMesh& zm)
 :
-    pointZone(word::null, 0, zm)
+    zone(),
+    zoneMesh_(zm)
 {}
 
 
@@ -99,7 +97,7 @@ Foam::pointZone::pointZone
     const pointZoneMesh& zm
 )
 :
-    zone(name, dict, this->labelsName, index),
+    zone(name, dict, pointZone::labelsName(), index),
     zoneMesh_(zm)
 {}
 
@@ -107,7 +105,19 @@ Foam::pointZone::pointZone
 Foam::pointZone::pointZone
 (
     const pointZone& originalZone,
-    const Foam::zero,
+    const pointZoneMesh& zm,
+    const label newIndex
+)
+:
+    zone(originalZone, newIndex),
+    zoneMesh_(zm)
+{}
+
+
+Foam::pointZone::pointZone
+(
+    const pointZone& originalZone,
+    Foam::zero,
     const pointZoneMesh& zm,
     const label newIndex
 )
@@ -120,12 +130,12 @@ Foam::pointZone::pointZone
 Foam::pointZone::pointZone
 (
     const pointZone& originalZone,
-    const Foam::zero,
+    Foam::zero,
-    const label index,
+    const label newIndex,
     const pointZoneMesh& zm
 )
 :
-    zone(originalZone, labelList(), index),
+    zone(originalZone, labelList(), newIndex),
     zoneMesh_(zm)
 {}
 
@@ -160,16 +170,17 @@ Foam::pointZone::pointZone
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
-Foam::label Foam::pointZone::whichPoint(const label globalPointID) const
+Foam::label Foam::pointZone::max_index() const noexcept
 {
-    return zone::localID(globalPointID);
+    return zoneMesh_.mesh().nPoints();
 }
 
 
-bool Foam::pointZone::checkDefinition(const bool report) const
+// void Foam::pointZone::sort()
-{
+// {
-    return zone::checkDefinition(zoneMesh_.mesh().points().size(), report);
+//     clearAddressing();
-}
+//     Foam::sort(static_cast<labelList&>(*this));
+// }
 
 
 bool Foam::pointZone::checkParallelSync(const bool report) const
@@ -226,18 +237,6 @@ bool Foam::pointZone::checkParallelSync(const bool report) const
 }
 
 
-void Foam::pointZone::writeDict(Ostream& os) const
-{
-    os.beginBlock(name());
-
-    os.writeEntry("type", type());
-    zoneIdentifier::write(os);
-    writeEntry(this->labelsName, os);
-
-    os.endBlock();
-}
-
-
 void Foam::pointZone::resetAddressing(pointZone&& zn)
 {
     if (this == &zn)
@@ -277,6 +276,13 @@ void Foam::pointZone::resetAddressing(labelList&& addr)
 }
 
 
+void Foam::pointZone::write(Ostream& os) const
+{
+    zone::write(os);
+    labelList::writeEntry(pointZone::labelsName(), os);
+}
+
+
 // * * * * * * * * * * * * * * * Member Operators  * * * * * * * * * * * * * //
 
 void Foam::pointZone::operator=(const pointZone& zn)

src/OpenFOAM/meshes/polyMesh/zones/pointZone/pointZone.H

@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011 OpenFOAM Foundation
-    Copyright (C) 2017-2023 OpenCFD Ltd.
+    Copyright (C) 2017-2025 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -77,8 +77,7 @@ public:
     // Static Data Members
 
         //- The name associated with the zone-labels dictionary entry
-        //- ("pointLabels")
+        static constexpr const char* labelsName() { return "pointLabels"; }
-        static const char * const labelsName;
 
 
     //- Runtime type information
@@ -145,13 +144,23 @@ public:
             const pointZoneMesh& zm
         );
 
-        //- Construct empty with original zone information (name, index, groups)
+        //- Copy construct with new mesh reference.
-        //- and mesh reference. Optionally specify a new index.
         pointZone
         (
             const pointZone& originalZone,
-            const Foam::zero,
             const pointZoneMesh& zm,
+            //! The new index (optional. -1 retains the original value)
+            const label newIndex = -1
+        );
+
+        //- Construct empty with original zone information (name, index, groups)
+        //- and mesh reference.
+        pointZone
+        (
+            const pointZone& originalZone,
+            Foam::zero,
+            const pointZoneMesh& zm,
+            //! The new index (optional. -1 retains the original value)
             const label newIndex = -1
         );
 
@@ -160,7 +169,8 @@ public:
         pointZone
         (
             const pointZone& originalZone,
-            const Foam::zero,
+            Foam::zero,
+            //! The new index (-1 retains the original value)
             const label index,
             const pointZoneMesh& zm
         );
@@ -171,6 +181,7 @@ public:
         (
             const pointZone& originalZone,
             const labelUList& addr,
+            //! The new index (-1 retains the original value)
             const label index,
             const pointZoneMesh& zm
         );
@@ -181,22 +192,29 @@ public:
         (
             const pointZone& originalZone,
             labelList&& addr,
+            //! The new index (-1 retains the original value)
             const label index,
             const pointZoneMesh& zm
         );
 
 
         //- Construct and return a clone, resetting the zone mesh
-        virtual autoPtr<pointZone> clone(const pointZoneMesh& zm) const
-        {
-            return autoPtr<pointZone>::New(*this, *this, index(), zm);
-        }
-
-        //- Construct and return a clone, resetting the point list
-        //- and zone mesh
         virtual autoPtr<pointZone> clone
         (
             const pointZoneMesh& zm,
+            //! The new index (optional. -1 retains the original value)
+            const label newIndex = -1
+        ) const
+        {
+            return autoPtr<pointZone>::New(*this, zm, newIndex);
+        }
+
+        //- Construct and return a clone,
+        //- resetting the point list and zone mesh
+        virtual autoPtr<pointZone> clone
+        (
+            const pointZoneMesh& zm,
+            //! The new index (-1 retains the original value)
             const label index,
             const labelUList& addr
         ) const
@@ -224,33 +242,35 @@ public:
 
     // Member Functions
 
+        //- The maximum index the zone may contain == mesh nPoints()
+        label max_index() const noexcept;
+
         //- Return reference to the zone mesh
         const pointZoneMesh& zoneMesh() const noexcept { return zoneMesh_; }
 
         //- The addressing (point IDs) used for the zone
-        const labelList& addressing() const noexcept
+        using zone::addressing;
+
+        //- The local index of the given mesh point, -1 if not in the zone
+        label whichPoint(const label meshPointID) const
         {
-            return static_cast<const labelList&>(*this);
+            return zone::localID(meshPointID);
         }
 
-        //- Helper function to re-direct to zone::localID(...)
-        label whichPoint(const label globalPointID) const;
 
+    // Checks
 
-        //- Check zone definition. Return true if in error.
+        //- Check zone definition.
-        virtual bool checkDefinition(const bool report = false) const;
+        //  \return True if any errors.
+        virtual bool checkDefinition(const bool report = false) const
+        {
+            return zone::checkDefinition(max_index(), report);
+        }
 
         //- Check whether zone is synchronised across coupled boundaries.
         //  \return True if any errors.
         virtual bool checkParallelSync(const bool report = false) const;
 
-        //- Correct patch after moving points
-        virtual void movePoints(const pointField&)
-        {}
-
-        //- Write dictionary
-        virtual void writeDict(Ostream& os) const;
-
 
     // Assign addressing
 
@@ -276,10 +296,31 @@ public:
         void operator=(labelList&& addr);
 
 
+    // Mesh Changes
+
+        //- Nothing to correct after moving points
+        virtual void movePoints(const pointField&)
+        {}
+
+
     // I-O
 
+        //- Write (dictionary entries)
+        virtual void write(Ostream& os) const;
+
         //- Ostream Operator
         friend Ostream& operator<<(Ostream& os, const pointZone& zn);
+
+
+    // Housekeeping
+
+        //- Deprecated(2025-09) Write dictionary
+        //  \deprecated(2025-09) Write dictionary
+        FOAM_DEPRECATED_FOR(2025-09, "write() or operator<<")
+        void writeDict(Ostream& os) const
+        {
+            os.beginBlock(name()); write(os); os.endBlock();
+        }
 };
 
 

src/OpenFOAM/meshes/polyMesh/zones/pointZone/pointZoneMeshFwd.H

@@ -41,7 +41,7 @@ namespace Foam
     class pointZone;
     class polyMesh;
 
-    template<class Zone, class MeshType> class ZoneMesh;
+    template<class ZoneType, class MeshType> class ZoneMesh;
     typedef ZoneMesh<pointZone, polyMesh> pointZoneMesh;
 }
 

src/OpenFOAM/meshes/polyMesh/zones/zone/zone.C

@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2017-2023 OpenCFD Ltd.
+    Copyright (C) 2017-2025 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -43,17 +43,13 @@ namespace Foam
 
 Foam::zone::zone()
 :
-    zoneIdentifier(),
+    zoneIdentifier()
-    labelList(),
-    lookupMapPtr_(nullptr)
 {}
 
 
 Foam::zone::zone(const word& name, const label index)
 :
-    zoneIdentifier(name, index),
+    zoneIdentifier(name, index)
-    labelList(),
-    lookupMapPtr_(nullptr)
 {}
 
 
@@ -91,9 +87,23 @@ Foam::zone::zone
     const label index
 )
 :
-    zoneIdentifier(name, dict, index),
+    zoneIdentifier(name, dict, index)
-    labelList(dict.get<labelList>(labelsName)),
+{
-    lookupMapPtr_(nullptr)
+    if (!labelsName.empty())
+    {
+        dict.readEntry<labelList>(labelsName, *this, keyType::LITERAL);
+    }
+}
+
+
+Foam::zone::zone
+(
+    const zone& originalZone,
+    const label newIndex
+)
+:
+    zoneIdentifier(originalZone, newIndex),
+    labelList(originalZone)
 {}
 
 
@@ -105,8 +115,7 @@ Foam::zone::zone
 )
 :
     zoneIdentifier(originalZone, newIndex),
-    labelList(addr),
+    labelList(addr)
-    lookupMapPtr_(nullptr)
 {}
 
 
@@ -118,8 +127,7 @@ Foam::zone::zone
 )
 :
     zoneIdentifier(originalZone, newIndex),
-    labelList(std::move(addr)),
+    labelList(std::move(addr))
-    lookupMapPtr_(nullptr)
 {}
 
 
@@ -131,8 +139,9 @@ const Foam::Map<Foam::label>& Foam::zone::lookupMap() const
     {
         const labelList& addr = *this;
 
-        lookupMapPtr_.reset(new Map<label>(2*addr.size()));
+        lookupMapPtr_.reset(new Map<label>());
         auto& map = *lookupMapPtr_;
+        map.reserve(addr.size());
 
         for (const label id : addr)
         {
@@ -150,6 +159,13 @@ Foam::label Foam::zone::localID(const label globalID) const
 }
 
 
+// void Foam::zone::sort()
+// {
+//     clearAddressing();
+//     Foam::sort(*this);
+// }
+
+
 void Foam::zone::clearAddressing()
 {
     lookupMapPtr_.reset(nullptr);
@@ -169,7 +185,8 @@ bool Foam::zone::checkDefinition(const label maxSize, const bool report) const
     bool hasError = false;
 
     // To check for duplicate entries
-    labelHashSet elems(2*size());
+    labelHashSet elems;
+    elems.reserve(addr.size());
 
     for (const label id : addr)
     {
@@ -182,8 +199,7 @@ bool Foam::zone::checkDefinition(const label maxSize, const bool report) const
                 SeriousErrorInFunction
                     << "Zone " << this->name()
                     << " contains invalid index label " << id << nl
-                    << "Valid index labels are 0.."
+                    << "Valid index labels are 0.." << (maxSize-1) << endl;
-                    << maxSize-1 << endl;
             }
             else
             {
@@ -208,8 +224,8 @@ bool Foam::zone::checkDefinition(const label maxSize, const bool report) const
 
 void Foam::zone::write(Ostream& os) const
 {
-    os  << nl << this->name()
+    os.writeEntry("type", type());
-        << nl << static_cast<const labelList&>(*this);
+    zoneIdentifier::write(os);
 }
 
 
@@ -217,7 +233,9 @@ void Foam::zone::write(Ostream& os) const
 
 Foam::Ostream& Foam::operator<<(Ostream& os, const zone& zn)
 {
-    zn.write(os);
+    os  << nl << zn.name()
+        << nl << static_cast<const labelList&>(zn);
+
     os.check(FUNCTION_NAME);
     return os;
 }

src/OpenFOAM/meshes/polyMesh/zones/zone/zone.H

@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2017-2023 OpenCFD Ltd.
+    Copyright (C) 2017-2025 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -80,7 +80,7 @@ public:
 
     // Constructors
 
-        //- Default construct
+        //- Default construct: empty zone with name="", index=0
         zone();
 
         //- Construct an empty zone with specified name and index
@@ -107,25 +107,36 @@ public:
         (
             const word& name,
             const dictionary& dict,
+            //! The lookup name for the labelList. Ignored if empty
             const word& labelsName,
             const label index
         );
 
-        //- Construct given the name of the original zone (name is used)
+        //- Copy construct with new index
-        //- with new addressing and index (-ve: retain zone index).
         zone
         (
             const zone& originalZone,
-            const labelUList& addr,
+            //! The new index (-1 retains the original value)
             const label index
         );
 
         //- Construct given the name of the original zone (name is used)
-        //- and (move) resetting addressing and index (-ve: retain zone index).
+        //- with new addressing and index
+        zone
+        (
+            const zone& originalZone,
+            const labelUList& addr,
+            //! The new index (-1 retains the original value)
+            const label index
+        );
+
+        //- Construct given the name of the original zone (name is used)
+        //- and (move) resetting addressing and index
         zone
         (
             const zone& originalZone,
             labelList&& addr,
+            //! The new index (-1 retains the original value)
             const label index
         );
 
@@ -166,19 +177,19 @@ public:
             const bool report = false
         ) const;
 
-        //- Correct patch after moving points
+
-        virtual void movePoints(const pointField& pts)
+    // Mesh Changes
+
+        //- Corrections after moving points
+        virtual void movePoints(const pointField&)
         {}
 
-        //- Write
-        virtual void write(Ostream& os) const;
-
-        //- Write dictionary
-        virtual void writeDict(Ostream& os) const = 0;
-
 
     // I-O
 
+        //- Write (dictionary entries)
+        virtual void write(Ostream& os) const;
+
         //- Ostream Operator
         friend Ostream& operator<<(Ostream& os, const zone& zn);
 };

src/dynamicMesh/fvMeshDistribute/fvMeshDistribute.C

@@ -1949,13 +1949,13 @@ Foam::autoPtr<Foam::mapDistributePolyMesh> Foam::fvMeshDistribute::distribute
     // Note that this is not necessary for redistributePar since that already
     // checks for it. However other use (e.g. mesh generators) might not.
     const wordList pointZoneNames(mergeWordList(mesh_.pointZones().names()));
-    reorderZones<pointZone>(pointZoneNames, mesh_.pointZones());
+    reorderZones(pointZoneNames, mesh_.pointZones());
 
     const wordList faceZoneNames(mergeWordList(mesh_.faceZones().names()));
-    reorderZones<faceZone>(faceZoneNames, mesh_.faceZones());
+    reorderZones(faceZoneNames, mesh_.faceZones());
 
     const wordList cellZoneNames(mergeWordList(mesh_.cellZones().names()));
-    reorderZones<cellZone>(cellZoneNames, mesh_.cellZones());
+    reorderZones(cellZoneNames, mesh_.cellZones());
 
 
     // Local environment of all boundary faces

src/dynamicMesh/fvMeshDistribute/fvMeshDistribute.H

@@ -98,12 +98,8 @@ class fvMeshDistribute
         static wordList mergeWordList(const wordList&);
 
         //- Reorder zones according to names
-        template<class ZoneType, class ZoneMesh>
+        template<class ZoneMesh>
-        void reorderZones
+        void reorderZones(const wordList& zoneNames, ZoneMesh& zones);
-        (
-            const wordList& zoneNames,
-            ZoneMesh& zones
-        );
 
 
         // Patch handling

src/dynamicMesh/fvMeshDistribute/fvMeshDistributeTemplates.C

@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2015-2023 OpenCFD Ltd.
+    Copyright (C) 2015-2025 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -30,7 +30,7 @@ License
 
 // * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
 
-template<class ZoneType, class ZoneMesh>
+template<class ZoneMesh>
 void Foam::fvMeshDistribute::reorderZones
 (
     const wordList& zoneNames,
@@ -39,41 +39,50 @@ void Foam::fvMeshDistribute::reorderZones
 {
     zones.clearAddressing();
 
+    typedef typename ZoneMesh::zone_type zone_type;
+
     // Shift old ones to new position
-    UPtrList<ZoneType> newZonePtrs(zoneNames.size());
+    PtrList<zone_type>& oldPtrs = zones;
+    PtrList<zone_type> newPtrs(zoneNames.size());
+
     forAll(zones, zonei)
     {
-        auto* zonePtr = zones.get(zonei);
+        if (!zones.get(zonei))
-        if (!zonePtr)
         {
-            FatalErrorInFunction << "Problem with zones " << zones.names()
+            FatalErrorInFunction
+                << "Problem with zone[" << zonei << "] " << zones.names()
                 << exit(FatalError);
         }
-        const label newIndex = zoneNames.find(zonePtr->name());
+    }
-        zonePtr->index() = newIndex;
+
-        newZonePtrs.set(newIndex, zonePtr);
+    forAll(zones, zonei)
+    {
+        // Take ownership
+        auto ptr = oldPtrs.release(zonei);
+        if (!ptr)
+        {
+            FatalErrorInFunction
+                << "Problem with zone[" << zonei << "] == nullptr" << nl
+                << exit(FatalError);
+        }
+
+        const label newIndex = zoneNames.find(ptr->name());
+        // Check if not found?
+        ptr->index() = newIndex;
+        newPtrs.set(newIndex, std::move(ptr));
     }
 
     // Add empty zones for unknown ones
-    forAll(newZonePtrs, i)
+    forAll(newPtrs, i)
     {
-        if (!newZonePtrs.get(i))
+        if (!newPtrs.get(i))
         {
-            newZonePtrs.set
+            newPtrs.emplace_set(i, zoneNames[i], i, zones);
-            (
-                i,
-                new ZoneType
-                (
-                    zoneNames[i],
-                    i,
-                    zones
-                )
-            );
         }
     }
 
     // Transfer
-    zones.swap(newZonePtrs);
+    oldPtrs = std::move(newPtrs);
 }
 
 

src/finiteArea/Make/files

@@ -11,6 +11,8 @@ faMesh/faMeshBoundaryHalo.C
 faMesh/faBoundaryMesh/faBoundaryMesh.C
 faMesh/faBoundaryMesh/faBoundaryMeshEntries.C
 
+faceZone = faMesh/zones/faceZone/faFaceZone.cxx
+
 faMesh/faMeshSubset/faMeshSubset.C
 faMesh/faMeshTools/faMeshTools.C
 faMesh/faMeshTools/faMeshToolsChecks.C

src/finiteArea/faMesh/zones/faceZone/faFaceZone.H

@@ -0,0 +1,280 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2025 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::faFaceZone
+
+Description
+    A subset of finite-area face elements.
+
+SourceFiles
+    faFaceZone.C
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef Foam_faFaceZone_H
+#define Foam_faFaceZone_H
+
+#include "zone.H"
+#include "faFaceZoneMeshFwd.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+// Forward Declarations
+class faFaceZone;
+Ostream& operator<<(Ostream& os, const faFaceZone& zn);
+
+/*---------------------------------------------------------------------------*\
+                           Class faFaceZone Declaration
+\*---------------------------------------------------------------------------*/
+
+class faFaceZone
+:
+    public zone
+{
+    // Private Data
+
+        //- Reference to zone list
+        const faFaceZoneMesh& zoneMesh_;
+
+
+public:
+
+    // Static Data Members
+
+        //- The name associated with the zone-labels dictionary entry
+        static constexpr const char* labelsName() { return "faceLabels"; }
+
+
+    //- Runtime type information
+    TypeName("faFaceZone");
+
+
+    // Constructors
+
+        //- No copy construct
+        faFaceZone(const faFaceZone&) = delete;
+
+        //- Construct an empty zone - name="", index=0
+        explicit faFaceZone(const faFaceZoneMesh& zm);
+
+        //- Construct an empty zone with specified name and index
+        faFaceZone
+        (
+            const word& name,
+            const label index,
+            const faFaceZoneMesh& zm
+        );
+
+        //- Construct from components
+        faFaceZone
+        (
+            const word& name,
+            const labelUList& addr,
+            const label index,
+            const faFaceZoneMesh& zm
+        );
+
+        //- Construct from components, transferring addressing
+        faFaceZone
+        (
+            const word& name,
+            labelList&& addr,
+            const label index,
+            const faFaceZoneMesh& zm
+        );
+
+        //- Construct from dictionary
+        faFaceZone
+        (
+            const word& name,
+            const dictionary& dict,
+            const label index,
+            const faFaceZoneMesh& zm
+        );
+
+        //- Copy construct with a new mesh reference
+        faFaceZone
+        (
+            const faFaceZone& originalZone,
+            const faFaceZoneMesh& zm,
+            //! The new index (optional. -1 retains the original value)
+            const label newIndex = -1
+        );
+
+        //- Construct empty with original zone information (name, index, groups)
+        //- and mesh reference.
+        faFaceZone
+        (
+            const faFaceZone& originalZone,
+            Foam::zero,
+            const faFaceZoneMesh& zm,
+            //! The new index (optional. -1 retains the original value)
+            const label newIndex = -1
+        );
+
+        //- Construct empty with original zone information (name, groups),
+        //- resetting the index and zone mesh reference.
+        faFaceZone
+        (
+            const faFaceZone& originalZone,
+            Foam::zero,
+            //! The new index (-1 retains the original value)
+            const label index,
+            const faFaceZoneMesh& zm
+        );
+
+        //- Construct with original zone information (name, groups),
+        //- resetting the face list, the index and zone mesh reference.
+        faFaceZone
+        (
+            const faFaceZone& originalZone,
+            const labelUList& addr,
+            //! The new index (-1 retains the original value)
+            const label index,
+            const faFaceZoneMesh& zm
+        );
+
+        //- Construct with original zone information (name, groups),
+        //- resetting the face list, the index and zone mesh reference.
+        faFaceZone
+        (
+            const faFaceZone& originalZone,
+            labelList&& addr,
+            //! The new index (-1 retains the original value)
+            const label index,
+            const faFaceZoneMesh& zm
+        );
+
+
+        //- Construct and return a clone, resetting the zone mesh
+        virtual autoPtr<faFaceZone> clone
+        (
+            const faFaceZoneMesh& zm,
+            //! The new index (optional. -1 retains the original value)
+            const label newIndex = -1
+        ) const
+        {
+            return autoPtr<faFaceZone>::New(*this, zm, newIndex);
+        }
+
+        //- Construct and return a clone,
+        //- resetting the face list and zone mesh
+        virtual autoPtr<faFaceZone> clone
+        (
+            const labelUList& addr,
+            //! The new index (-1 retains the original value)
+            const label index,
+            const faFaceZoneMesh& zm
+        ) const
+        {
+            return autoPtr<faFaceZone>::New(*this, addr, index, zm);
+        }
+
+
+    //- Destructor
+    virtual ~faFaceZone() = default;
+
+
+    // Member Functions
+
+        //- The maximum index the zone may contain == mesh nFaces()
+        label max_index() const noexcept;
+
+        //- Return reference to the zone mesh
+        const faFaceZoneMesh& zoneMesh() const noexcept { return zoneMesh_; }
+
+        //- The addressing (face IDs) used for the zone
+        using zone::addressing;
+
+        //- The local index of the given mesh face, -1 if not in the zone
+        label whichFace(const label meshFaceID) const
+        {
+            return zone::localID(meshFaceID);
+        }
+
+
+    // Checks
+
+        //- Check zone definition. Return true if in error.
+        virtual bool checkDefinition(const bool report = false) const
+        {
+            return zone::checkDefinition(max_index(), report);
+        }
+
+        //- Check whether zone is synchronised across coupled boundaries.
+        //  \return True if any errors.
+        virtual bool checkParallelSync(const bool report = false) const
+        {
+            return false;
+        }
+
+
+    // Assign addressing
+
+        //- Move reset addressing from another zone
+        virtual void resetAddressing(faFaceZone&& zn);
+
+        //- Copy reset addressing from another zone
+        virtual void resetAddressing(const faFaceZone& zn);
+
+        //- Copy assign addressing
+        virtual void resetAddressing(const labelUList& addr);
+
+        //- Move assign addressing
+        virtual void resetAddressing(labelList&& addr);
+
+        //- Assign addressing, clearing demand-driven data
+        void operator=(const faFaceZone& zn);
+
+        //- Assign addressing, clearing demand-driven data
+        void operator=(const labelUList& addr);
+
+        //- Move assign addressing, clearing demand-driven data
+        void operator=(labelList&& addr);
+
+
+    // I-O
+
+        //- Write (dictionary entries)
+        virtual void write(Ostream& os) const;
+
+        //- Ostream Operator
+        friend Ostream& operator<<(Ostream& os, const faFaceZone& zn);
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //

src/finiteArea/faMesh/zones/faceZone/faFaceZone.cxx

@@ -0,0 +1,259 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2025 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 "faFaceZone.H"
+#include "faFaceZoneMesh.H"
+#include "faMesh.H"
+#include "IOstream.H"
+// #include "addToRunTimeSelectionTable.H"
+
+// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
+
+namespace Foam
+{
+    defineTypeNameAndDebug(faFaceZone, 0);
+    // defineRunTimeSelectionTable(faFaceZone, dictionary);
+    // addToRunTimeSelectionTable(faFaceZone, faFaceZone, dictionary);
+}
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+Foam::faFaceZone::faFaceZone(const faFaceZoneMesh& zm)
+:
+    zone(),
+    zoneMesh_(zm)
+{}
+
+
+Foam::faFaceZone::faFaceZone
+(
+    const word& name,
+    const label index,
+    const faFaceZoneMesh& zm
+)
+:
+    zone(name, index),
+    zoneMesh_(zm)
+{}
+
+
+Foam::faFaceZone::faFaceZone
+(
+    const word& name,
+    const labelUList& addr,
+    const label index,
+    const faFaceZoneMesh& zm
+)
+:
+    zone(name, addr, index),
+    zoneMesh_(zm)
+{}
+
+
+Foam::faFaceZone::faFaceZone
+(
+    const word& name,
+    labelList&& addr,
+    const label index,
+    const faFaceZoneMesh& zm
+)
+:
+    zone(name, std::move(addr), index),
+    zoneMesh_(zm)
+{}
+
+
+Foam::faFaceZone::faFaceZone
+(
+    const word& name,
+    const dictionary& dict,
+    const label index,
+    const faFaceZoneMesh& zm
+)
+:
+    zone(name, dict, faFaceZone::labelsName(), index),
+    zoneMesh_(zm)
+{}
+
+
+Foam::faFaceZone::faFaceZone
+(
+    const faFaceZone& originalZone,
+    const faFaceZoneMesh& zm,
+    const label newIndex
+)
+:
+    zone(originalZone, newIndex),
+    zoneMesh_(zm)
+{}
+
+
+Foam::faFaceZone::faFaceZone
+(
+    const faFaceZone& originalZone,
+    Foam::zero,
+    const faFaceZoneMesh& zm,
+    const label newIndex
+)
+:
+    zone(originalZone, labelList(), newIndex),
+    zoneMesh_(zm)
+{}
+
+
+Foam::faFaceZone::faFaceZone
+(
+    const faFaceZone& originalZone,
+    Foam::zero,
+    const label index,
+    const faFaceZoneMesh& zm
+)
+:
+    zone(originalZone, labelList(), index),
+    zoneMesh_(zm)
+{}
+
+
+Foam::faFaceZone::faFaceZone
+(
+    const faFaceZone& originalZone,
+    const labelUList& addr,
+    const label index,
+    const faFaceZoneMesh& zm
+)
+:
+    faFaceZone(originalZone, Foam::zero{}, index, zm)
+{
+    labelList::operator=(addr);
+}
+
+
+Foam::faFaceZone::faFaceZone
+(
+    const faFaceZone& originalZone,
+    labelList&& addr,
+    const label index,
+    const faFaceZoneMesh& zm
+)
+:
+    faFaceZone(originalZone, Foam::zero{}, index, zm)
+{
+    labelList::transfer(addr);
+}
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+Foam::label Foam::faceZonecellZone::max_index() const noexcept
+{
+    return zoneMesh_.mesh().nFaces();
+}
+
+
+bool Foam::faFaceZone::checkDefinition(const bool report) const
+{
+    return zone::checkDefinition(max_index(), report);
+}
+
+
+void Foam::faFaceZone::resetAddressing(faFaceZone&& zn)
+{
+    if (this == &zn)
+    {
+        return;  // Self-assignment is a no-op
+    }
+
+    clearAddressing();
+    labelList::transfer(static_cast<labelList&>(zn));
+    zn.clearAddressing();
+}
+
+
+void Foam::faFaceZone::resetAddressing(const faFaceZone& zn)
+{
+    if (this == &zn)
+    {
+        return;  // Self-assignment is a no-op
+    }
+
+    clearAddressing();
+    labelList::operator=(static_cast<const labelList&>(zn));
+}
+
+
+void Foam::faFaceZone::resetAddressing(const labelUList& addr)
+{
+    clearAddressing();
+    labelList::operator=(addr);
+}
+
+
+void Foam::faFaceZone::resetAddressing(labelList&& addr)
+{
+    clearAddressing();
+    labelList::transfer(addr);
+}
+
+
+void Foam::faFaceZone::write(Ostream& os) const
+{
+    zone::write(os);
+    labelList::writeEntry(faFaceZone::labelsName(), os);
+}
+
+
+// * * * * * * * * * * * * * * * Member Operators  * * * * * * * * * * * * * //
+
+void Foam::faFaceZone::operator=(const faFaceZone& zn)
+{
+    resetAddressing(zn);
+}
+
+
+void Foam::faFaceZone::operator=(const labelUList& addr)
+{
+    resetAddressing(addr);
+}
+
+
+void Foam::faFaceZone::operator=(labelList&& addr)
+{
+    resetAddressing(std::move(addr));
+}
+
+
+// * * * * * * * * * * * * * * * Ostream Operator  * * * * * * * * * * * * * //
+
+Foam::Ostream& Foam::operator<<(Ostream& os, const faFaceZone& zn)
+{
+    zn.write(os);
+    os.check(FUNCTION_NAME);
+    return os;
+}
+
+
+// ************************************************************************* //

src/finiteArea/faMesh/zones/faceZone/faFaceZoneMesh.H

@@ -0,0 +1,40 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2025 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/>.
+
+Description
+    Foam::faFaceZoneMesh
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef Foam_faFaceZoneMesh_H
+#define Foam_faFaceZoneMesh_H
+
+#include "ZoneMesh.H"
+#include "faFaceZone.H"
+#include "faFaceZoneMeshFwd.H"
+
+#endif
+
+// ************************************************************************* //

src/finiteArea/faMesh/zones/faceZone/faFaceZoneMeshFwd.H

@@ -0,0 +1,52 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2025 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::faFaceZone
+
+Description
+    A ZoneMesh with faFaceZone content on a faMesh
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef Foam_faFaceZoneMeshFwd_H
+#define Foam_faFaceZoneMeshFwd_H_H
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+    class faFaceZone;
+    class faMesh;
+
+    template<class ZoneType, class MeshType> class ZoneMesh;
+    typedef ZoneMesh<faFaceZone, faMesh> faFaceZoneMesh;
+}
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //