diff --git a/src/conversion/vtk/output/foamVtkInternalWriter.C b/src/conversion/vtk/output/foamVtkInternalWriter.C
index af675ce176..0d43a65c50 100644
--- a/src/conversion/vtk/output/foamVtkInternalWriter.C
+++ b/src/conversion/vtk/output/foamVtkInternalWriter.C
@@ -711,12 +711,7 @@ bool Foam::vtk::internalWriter::writeProcIDs()
         // Per-processor ids
         for (label proci=0; proci < Pstream::nProcs(); ++proci)
         {
-            label len = procMaps.localSize(proci);
-
-            while (len--)
-            {
-                format().write(proci);
-            }
+            vtk::write(format(), proci, procMaps.localSize(proci));
         }
 
         format().flush();
diff --git a/src/conversion/vtk/output/foamVtkPatchWriter.C b/src/conversion/vtk/output/foamVtkPatchWriter.C
index b47c59cb32..890b4fd3ae 100644
--- a/src/conversion/vtk/output/foamVtkPatchWriter.C
+++ b/src/conversion/vtk/output/foamVtkPatchWriter.C
@@ -587,13 +587,7 @@ void Foam::vtk::patchWriter::writePatchIDs()
     {
         for (const label patchId : patchIDs_)
         {
-            label count = patches[patchId].size();
-            const label val = patchId;
-
-            while (count--)
-            {
-                format().write(val);
-            }
+            vtk::write(format(), patchId, patches[patchId].size());
         }
     }
 
@@ -615,16 +609,13 @@ void Foam::vtk::patchWriter::writePatchIDs()
 
                 fromSlave >> recv;
 
-                for (label i=0; i < recv.size(); ++i)
+                // Receive as [size, id] pairs
+                for (label i=0; i < recv.size(); i += 2)
                 {
-                    label count = recv[i];
-                    ++i;
-                    const label val = recv[i];
+                    const label len = recv[i];
+                    const label val = recv[i+1];
 
-                    while (count--)
-                    {
-                        format().write(val);
-                    }
+                    vtk::write(format(), val, len);
                 }
             }
         }
@@ -722,12 +713,7 @@ bool Foam::vtk::patchWriter::writeProcIDs()
             // Per-processor ids
             for (label proci=0; proci < Pstream::nProcs(); ++proci)
             {
-                label len = procSizes.localSize(proci);
-
-                while (len--)
-                {
-                    format().write(proci);
-                }
+                vtk::write(format(), proci, procSizes.localSize(proci));
             }
 
             good = true;
@@ -735,14 +721,7 @@ bool Foam::vtk::patchWriter::writeProcIDs()
     }
     else
     {
-        const label proci = Pstream::myProcNo();
-
-        label len = nLocalFaces_;
-
-        while (len--)
-        {
-            format().write(proci);
-        }
+        vtk::write(format(), Pstream::myProcNo(), nLocalFaces_);
 
         good = true;
     }
@@ -811,16 +790,11 @@ bool Foam::vtk::patchWriter::writeNeighIDs()
     {
         for (const label patchId : patchIDs_)
         {
-            label count = patches[patchId].size();
-
             const auto* pp = isA<processorPolyPatch>(patches[patchId]);
 
-            const label val = (pp ?  pp->neighbProcNo() : -1);
+            const label val = (pp ? pp->neighbProcNo() : -1);
 
-            while (count--)
-            {
-                format().write(val);
-            }
+            vtk::write(format(), val, patches[patchId].size());
         }
 
         good = true;
@@ -844,16 +818,13 @@ bool Foam::vtk::patchWriter::writeNeighIDs()
 
                 fromSlave >> recv;
 
-                for (label i=0; i < recv.size(); ++i)
+                // Receive as [size, id] pairs
+                for (label i=0; i < recv.size(); i += 2)
                 {
-                    label count = recv[i];
-                    ++i;
-                    const label val = recv[i];
+                    const label len = recv[i];
+                    const label val = recv[i+1];
 
-                    while (count--)
-                    {
-                        format().write(val);
-                    }
+                    vtk::write(format(), val, len);
                 }
             }
         }
diff --git a/src/fileFormats/vtk/file/foamVtkFileWriterTemplates.C b/src/fileFormats/vtk/file/foamVtkFileWriterTemplates.C
index 606d522c4a..00a51fbceb 100644
--- a/src/fileFormats/vtk/file/foamVtkFileWriterTemplates.C
+++ b/src/fileFormats/vtk/file/foamVtkFileWriterTemplates.C
@@ -81,10 +81,7 @@ void Foam::vtk::fileWriter::writeUniform
 
     if (format_)
     {
-        for (label i=0; i < nValues; ++i)
-        {
-            vtk::write(format(), val);
-        }
+        vtk::write(format(), val, nValues);
     }
 
     if (format_)
diff --git a/src/fileFormats/vtk/output/foamVtkOutput.C b/src/fileFormats/vtk/output/foamVtkOutput.C
index 5311fd0db1..25eeb50148 100644
--- a/src/fileFormats/vtk/output/foamVtkOutput.C
+++ b/src/fileFormats/vtk/output/foamVtkOutput.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2016-2018 OpenCFD Ltd.
+    \\  /    A nd           | Copyright (C) 2016-2019 OpenCFD Ltd.
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -89,6 +89,22 @@ Foam::vtk::newFormatter
 }
 
 
+void Foam::vtk::writeIdentity
+(
+    vtk::formatter& fmt,
+    const label len,
+    label start
+)
+{
+    // No nComponents for label, so use fmt.write() directly
+    for (label i=0; i < len; ++i)
+    {
+        fmt.write(start);
+        ++start;
+    }
+}
+
+
 void Foam::vtk::writeList
 (
     vtk::formatter& fmt,
diff --git a/src/fileFormats/vtk/output/foamVtkOutput.H b/src/fileFormats/vtk/output/foamVtkOutput.H
index 37cc0b5540..832fa0049a 100644
--- a/src/fileFormats/vtk/output/foamVtkOutput.H
+++ b/src/fileFormats/vtk/output/foamVtkOutput.H
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2016-2018 OpenCFD Ltd.
+    \\  /    A nd           | Copyright (C) 2016-2019 OpenCFD Ltd.
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -84,48 +84,32 @@ namespace vtk
     );
 
 
-    //- Write a list of uint8_t values.
+    //- Write an identity list of labels.
     //  The output does not include the payload size.
-    void writeList
-    (
-        vtk::formatter& fmt,
-        const UList<uint8_t>& values
-    );
+    void writeIdentity(vtk::formatter& fmt, const label len, label start=0);
 
     //- Write a list of uint8_t values.
     //  The output does not include the payload size.
-    void writeListParallel
-    (
-        vtk::formatter& fmt,
-        const UList<uint8_t>& values
-    );
+    void writeList(vtk::formatter& fmt, const UList<uint8_t>& values);
 
-    //- Write a value component-wise.
+    //- Write a list of uint8_t values.
+    //  The output does not include the payload size.
+    void writeListParallel(vtk::formatter& fmt, const UList<uint8_t>& values);
+
+    //- Component-wise write of a value (N times)
     template<class Type>
-    inline void write
-    (
-        vtk::formatter& fmt,
-        const Type& val
-    );
+    inline void write(vtk::formatter& fmt, const Type& val, const label n=1);
 
 
     //- Write a list of values.
     //  The output does not include the payload size.
     template<class Type>
-    void writeList
-    (
-        vtk::formatter& fmt,
-        const UList<Type>& values
-    );
+    void writeList(vtk::formatter& fmt, const UList<Type>& values);
 
     //- Write a list of values.
     //  The output does not include the payload size.
     template<class Type, unsigned N>
-    void writeList
-    (
-        vtk::formatter& fmt,
-        const FixedList<Type, N>& values
-    );
+    void writeList(vtk::formatter& fmt, const FixedList<Type, N>& values);
 
 
     //- Write a list of values via indirect addressing.
@@ -327,22 +311,6 @@ namespace legacy
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
-//- Template specialization for symmTensor ordering
-template<>
-inline void write(vtk::formatter& fmt, const symmTensor& val)
-{
-    // symmTensor ( XX, XY, XZ, YY, YZ, ZZ )
-    // VTK order  ( XX, YY, ZZ, XY, YZ, XZ ) -> (0, 3, 5, 1, 4, 2)
-
-    fmt.write(component(val, 0)); // XX
-    fmt.write(component(val, 3)); // YY
-    fmt.write(component(val, 5)); // ZZ
-    fmt.write(component(val, 1)); // XY
-    fmt.write(component(val, 4)); // YZ
-    fmt.write(component(val, 2)); // XZ
-}
-
-
 } // End namespace vtk
 } // End namespace Foam
 
diff --git a/src/fileFormats/vtk/output/foamVtkOutputI.H b/src/fileFormats/vtk/output/foamVtkOutputI.H
index 40b5275737..735277a090 100644
--- a/src/fileFormats/vtk/output/foamVtkOutputI.H
+++ b/src/fileFormats/vtk/output/foamVtkOutputI.H
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2017-2018 OpenCFD Ltd.
+    \\  /    A nd           | Copyright (C) 2017-2019 OpenCFD Ltd.
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -32,27 +32,54 @@ namespace vtk
 
 //- Template specialization for label
 template<>
-inline void write<label>(vtk::formatter& fmt, const label& val)
+inline void write<label>(vtk::formatter& fmt, const label& val, const label n)
 {
-    fmt.write(val);
+    for (label i=0; i < n; ++i)
+    {
+        fmt.write(val);
+    }
 }
 
 
 //- Template specialization for float
 template<>
-inline void write<float>(vtk::formatter& fmt, const float& val)
+inline void write<float>(vtk::formatter& fmt, const float& val, const label n)
 {
-    fmt.write(val);
+    for (label i=0; i < n; ++i)
+    {
+        fmt.write(val);
+    }
 }
 
 
 //- Template specialization for double
 template<>
-inline void write<double>(vtk::formatter& fmt, const double& val)
+inline void write<double>(vtk::formatter& fmt, const double& val, const label n)
 {
-    fmt.write(val);
+    for (label i=0; i < n; ++i)
+    {
+        fmt.write(val);
+    }
 }
 
+
+//- Template specialization for symmTensor ordering
+//  VTK order is (XX, YY, ZZ, XY, YZ, XZ)
+template<>
+inline void write(vtk::formatter& fmt, const symmTensor& val, const label n)
+{
+    for (label i=0; i < n; ++i)
+    {
+        fmt.write(component(val, symmTensor::XX));
+        fmt.write(component(val, symmTensor::YY));
+        fmt.write(component(val, symmTensor::ZZ));
+        fmt.write(component(val, symmTensor::XY));
+        fmt.write(component(val, symmTensor::YZ));
+        fmt.write(component(val, symmTensor::XZ));
+    }
+}
+
+
 } // End namespace vtk
 } // End namespace Foam
 
diff --git a/src/fileFormats/vtk/output/foamVtkOutputTemplates.C b/src/fileFormats/vtk/output/foamVtkOutputTemplates.C
index 46781934e8..ecbeff2ac9 100644
--- a/src/fileFormats/vtk/output/foamVtkOutputTemplates.C
+++ b/src/fileFormats/vtk/output/foamVtkOutputTemplates.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2016-2018 OpenCFD Ltd.
+    \\  /    A nd           | Copyright (C) 2016-2019 OpenCFD Ltd.
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -32,13 +32,18 @@ template<class Type>
 inline void Foam::vtk::write
 (
     vtk::formatter& fmt,
-    const Type& val
+    const Type& val,
+    const label n
 )
 {
     const direction nCmpt = pTraits<Type>::nComponents;
-    for (direction cmpt=0; cmpt < nCmpt; ++cmpt)
+
+    for (label i=0; i < n; ++i)
     {
-        fmt.write(component(val, cmpt));
+        for (direction cmpt=0; cmpt < nCmpt; ++cmpt)
+        {
+            fmt.write(component(val, cmpt));
+        }
     }
 }
 
diff --git a/src/functionObjects/lagrangian/vtkCloud/vtkCloud.C b/src/functionObjects/lagrangian/vtkCloud/vtkCloud.C
index 6fdb41b00b..9abd8f0926 100644
--- a/src/functionObjects/lagrangian/vtkCloud/vtkCloud.C
+++ b/src/functionObjects/lagrangian/vtkCloud/vtkCloud.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2018 OpenCFD Ltd.
+    \\  /    A nd           | Copyright (C) 2018-2019 OpenCFD Ltd.
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -69,10 +69,8 @@ void Foam::functionObjects::vtkCloud::writeVerts
         format().beginDataArray<label>(vtk::dataArrayAttr::CONNECTIVITY);
         format().writeSize(payLoad);
 
-        for (label i=0; i < nTotParcels; ++i)
-        {
-            format().write(i);
-        }
+        vtk::writeIdentity(format(), nTotParcels);
+
         format().flush();
         format().endDataArray();
     }
@@ -85,10 +83,8 @@ void Foam::functionObjects::vtkCloud::writeVerts
         format().beginDataArray<label>(vtk::dataArrayAttr::OFFSETS);
         format().writeSize(payLoad);
 
-        for (label i=0; i < nTotParcels; ++i)
-        {
-            format().write(i+1);
-        }
+        vtk::writeIdentity(format(), nTotParcels, 1);
+
         format().flush();
         format().endDataArray();
     }
diff --git a/src/lagrangian/intermediate/conversion/vtk/foamVtkLagrangianWriter.C b/src/lagrangian/intermediate/conversion/vtk/foamVtkLagrangianWriter.C
index 792e3757bd..dd2b3b3685 100644
--- a/src/lagrangian/intermediate/conversion/vtk/foamVtkLagrangianWriter.C
+++ b/src/lagrangian/intermediate/conversion/vtk/foamVtkLagrangianWriter.C
@@ -43,9 +43,9 @@ Foam::pointField Foam::vtk::lagrangianWriter::positions() const
 
     auto outIter = pts.begin();
 
-    forAllConstIters(parcels, iter)
+    for (const auto& p : parcels)
     {
-        *outIter = iter().position();
+        *outIter = p.position();
         ++outIter;
     }
 
@@ -74,10 +74,8 @@ void Foam::vtk::lagrangianWriter::writeVerts()
         format().beginDataArray<label>(vtk::dataArrayAttr::CONNECTIVITY);
         format().writeSize(payLoad);
 
-        for (label i=0; i < nVerts; ++i)
-        {
-            format().write(i);
-        }
+        vtk::writeIdentity(format(), nVerts);
+
         format().flush();
         format().endDataArray();
     }
@@ -90,10 +88,8 @@ void Foam::vtk::lagrangianWriter::writeVerts()
         format().beginDataArray<label>(vtk::dataArrayAttr::OFFSETS);
         format().writeSize(payLoad);
 
-        for (label i=0; i < nVerts; ++i)
-        {
-            format().write(i+1);
-        }
+        vtk::writeIdentity(format(), nVerts, 1);
+
         format().flush();
         format().endDataArray();
     }
diff --git a/src/lumpedPointMotion/lumpedPointMovementWriter.C b/src/lumpedPointMotion/lumpedPointMovementWriter.C
index 3cc17656a6..0a3266dfbc 100644
--- a/src/lumpedPointMotion/lumpedPointMovementWriter.C
+++ b/src/lumpedPointMotion/lumpedPointMovementWriter.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2016-2017 OpenCFD Ltd.
+    \\  /    A nd           | Copyright (C) 2016-2019 OpenCFD Ltd.
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -100,10 +100,8 @@ void Foam::lumpedPointMovement::writeForcesAndMomentsVTP
             format().beginDataArray<label>(vtk::dataArrayAttr::CONNECTIVITY);
             format().writeSize(payLoad);
 
-            for (label i=0; i<nPoints; ++i)
-            {
-                format().write(i);
-            }
+            vtk::writeIdentity(format(), nPoints);
+
             format().flush();
 
             format().endDataArray();
@@ -119,10 +117,8 @@ void Foam::lumpedPointMovement::writeForcesAndMomentsVTP
             format().beginDataArray<label>(vtk::dataArrayAttr::OFFSETS);
             format().writeSize(payLoad);
 
-            for (label i=0; i<nPoints; ++i)
-            {
-                format().write(i+1);
-            }
+            vtk::writeIdentity(format(), nPoints, 1);
+
             format().flush();
 
             format().endDataArray();
@@ -284,10 +280,8 @@ void Foam::lumpedPointMovement::writeZonesVTP
             format().beginDataArray<label>("zoneId");
             format().writeSize(payLoad);
 
-            forAll(pp, facei)
-            {
-                format().write(zoneI);
-            }
+            vtk::write(format(), zoneI, pp.size());
+
             format().flush();
 
             format().endDataArray();
diff --git a/src/lumpedPointMotion/lumpedPointStateWriter.C b/src/lumpedPointMotion/lumpedPointStateWriter.C
index 1af7503e15..30bce4a051 100644
--- a/src/lumpedPointMotion/lumpedPointStateWriter.C
+++ b/src/lumpedPointMotion/lumpedPointStateWriter.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2016-2017 OpenCFD Ltd.
+    \\  /    A nd           | Copyright (C) 2016-2019 OpenCFD Ltd.
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -25,6 +25,7 @@ License
 
 #include "lumpedPointState.H"
 #include "OFstream.H"
+#include "sliceRange.H"
 #include "axesRotation.H"
 #include "coordinateSystem.H"
 #include "foamVtkOutput.H"
@@ -106,10 +107,8 @@ void Foam::lumpedPointState::writeVTP
             format().beginDataArray<label>(vtk::dataArrayAttr::CONNECTIVITY);
             format().writeSize(payLoad);
 
-            forAll(points_, i)
-            {
-                format().write(i);
-            }
+            vtk::writeIdentity(format(), points_.size());
+
             format().flush();
 
             format().endDataArray();
@@ -125,10 +124,8 @@ void Foam::lumpedPointState::writeVTP
             format().beginDataArray<label>(vtk::dataArrayAttr::OFFSETS);
             format().writeSize(payLoad);
 
-            forAll(points_, i)
-            {
-                format().write(i+1);
-            }
+            vtk::writeIdentity(format(), points_.size(), 1);
+
             format().flush();
 
             format().endDataArray();
@@ -150,10 +147,8 @@ void Foam::lumpedPointState::writeVTP
             format().beginDataArray<label>(vtk::dataArrayAttr::CONNECTIVITY);
             format().writeSize(payLoad);
 
-            forAll(points_, i)
-            {
-                format().write(i);
-            }
+            vtk::writeIdentity(format(), points_.size());
+
             format().flush();
 
             format().endDataArray();
@@ -256,10 +251,8 @@ void Foam::lumpedPointState::writeVTP
             format().beginDataArray<label>(vtk::dataArrayAttr::CONNECTIVITY);
             format().writeSize(payLoad);
 
-            for (label i=0; i < 4*nPolys; ++i)
-            {
-                format().write(i);
-            }
+            vtk::writeIdentity(format(), 4*nPolys);
+
             format().flush();
 
             format().endDataArray();
@@ -275,9 +268,8 @@ void Foam::lumpedPointState::writeVTP
             format().beginDataArray<label>(vtk::dataArrayAttr::OFFSETS);
             format().writeSize(payLoad);
 
-            for (label i=0; i < nPolys; ++i)
+            for (const label off : sliceRange(4, nPolys, 4))
             {
-                const label off = 4 * (i+1);
                 format().write(off);
             }
             format().flush();
@@ -297,10 +289,8 @@ void Foam::lumpedPointState::writeVTP
             format().beginDataArray<label>("zoneId");
             format().writeSize(payLoad);
 
-            for (label i=0; i < nPolys; ++i)
-            {
-                format().write(i);
-            }
+            vtk::writeIdentity(format(), nPolys);
+
             format().flush();
 
             format().endDataArray();
diff --git a/src/surfMesh/surfaceFormats/vtk/VTKsurfaceFormatCore.C b/src/surfMesh/surfaceFormats/vtk/VTKsurfaceFormatCore.C
index 00556c8f0c..e74a9a81b2 100644
--- a/src/surfMesh/surfaceFormats/vtk/VTKsurfaceFormatCore.C
+++ b/src/surfMesh/surfaceFormats/vtk/VTKsurfaceFormatCore.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2017-2018 OpenCFD Ltd.
+    \\  /    A nd           | Copyright (C) 2004-2019 OpenCFD Ltd.
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -86,7 +86,7 @@ void Foam::fileFormats::VTKsurfaceFormatCore::writeCellData
 
     // Number of faces covered by the zones
     label nFaces = 0;
-    for (const auto& z : zones)
+    for (const surfZone& z : zones)
     {
         nFaces += z.size();
     }
@@ -95,12 +95,9 @@ void Foam::fileFormats::VTKsurfaceFormatCore::writeCellData
     vtk::legacy::intField<1>(format, "region", nFaces); // 1 component
 
     label zoneId = 0;
-    for (const surfZone& zone : zones)
+    for (const surfZone& z : zones)
     {
-        forAll(zone, i)
-        {
-            format.write(zoneId);
-        }
+        vtk::write(format, zoneId, z.size());
         ++zoneId;
     }
     format.flush();
diff --git a/src/surfMesh/surfaceFormats/vtp/VTPsurfaceFormatCore.C b/src/surfMesh/surfaceFormats/vtp/VTPsurfaceFormatCore.C
index 5d927c347c..893744a0ab 100644
--- a/src/surfMesh/surfaceFormats/vtp/VTPsurfaceFormatCore.C
+++ b/src/surfMesh/surfaceFormats/vtp/VTPsurfaceFormatCore.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2017-2018 OpenCFD Ltd.
+    \\  /    A nd           | Copyright (C) 2017-2019 OpenCFD Ltd.
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -121,7 +121,7 @@ void Foam::fileFormats::VTPsurfaceFormatCore::writeCellData
 
     // Number of faces covered by the zones
     label nFaces = 0;
-    for (const auto& z : zones)
+    for (const surfZone& z : zones)
     {
         nFaces += z.size();
     }
@@ -133,12 +133,9 @@ void Foam::fileFormats::VTPsurfaceFormatCore::writeCellData
     format.writeSize(payLoad);
 
     label zoneId = 0;
-    for (const surfZone& zone : zones)
+    for (const surfZone& z : zones)
     {
-        forAll(zone, i)
-        {
-            format.write(zoneId);
-        }
+        vtk::write(format, zoneId, z.size());
         ++zoneId;
     }