diff --git a/applications/test/pTraits/Test-pTraits.C b/applications/test/pTraits/Test-pTraits.C
index d1a4f59bb7..6b4c4a5a54 100644
--- a/applications/test/pTraits/Test-pTraits.C
+++ b/applications/test/pTraits/Test-pTraits.C
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011 OpenFOAM Foundation
+    Copyright (C) 2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -29,9 +30,12 @@ Description
 
 #include "IOstreams.H"
 #include "pTraits.H"
+#include "contiguous.H"
+#include "boolVector.H"  // A FixedList pretending to be a vector
 #include "vector.H"
 #include "tensor.H"
 #include "uLabel.H"
+#include "Switch.H"
 
 #include <type_traits>
 
@@ -40,14 +44,72 @@ using namespace Foam;
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 // Main program:
 
+//- Test if Type has typeName member
+template<class T, class = void>
+struct has_typeName : std::false_type {};
+
+//- Test if Type has typeName member
+
+template<class T>
+struct has_typeName<T, stdFoam::void_t<decltype(pTraits<T>::typeName)>>
+:
+    std::true_type
+{};
+
+
+template<class T>
+typename std::enable_if<has_typeName<T>::value, void>::type
+printTypeName()
+{
+    Info<< pTraits<T>::typeName;
+}
+
+template<class T>
+typename std::enable_if<!has_typeName<T>::value, void>::type
+printTypeName()
+{
+    Info<< typeid(T).name();
+}
+
+
+template<class T, class = void>
+struct has_zero_one : std::false_type {};
+
+template<class T>
+struct has_zero_one
+<
+    T,
+    stdFoam::void_t<decltype(pTraits<T>::zero), decltype(pTraits<T>::one)>
+> : std::true_type {};
+
+
+template<class T>
+typename std::enable_if<has_zero_one<T>::value, void>::type
+printMinMaxRange()
+{
+    Info<< " zero=" << pTraits<T>::zero
+        << " one=" << pTraits<T>::one;
+}
+
+template<class T>
+typename std::enable_if<!has_zero_one<T>::value, void>::type
+printMinMaxRange()
+{}
+
+
 template<class T>
 void printTraits()
 {
-    Info<< pTraits<T>::typeName
-        << ": zero=" << pTraits<T>::zero
-        << " one=" << pTraits<T>::one
-        << " integral=" << std::is_integral<T>::value
+    printTypeName<T>();
+    printMinMaxRange<T>();
+
+    Info<< " integral=" << std::is_integral<T>::value
         << " floating=" << std::is_floating_point<T>::value
+        << " rank=" << pTraits_rank<T>::value
+        << " nComponents=" << pTraits_nComponents<T>::value
+        << " vector-space=" << Switch::name(is_vectorspace<T>::value)
+        << " is_label=" << Switch::name(is_contiguous_label<T>::value)
+        << " is_scalar=" << Switch::name(is_contiguous_scalar<T>::value)
         << endl;
 }
 
@@ -69,6 +131,9 @@ int main()
     printTraits<scalar>();
     printTraits<vector>();
     printTraits<tensor>();
+    printTraits<boolVector>();
+    printTraits<word>();
+    printTraits<std::string>();
 
     {
         pTraits<bool> b(true);
diff --git a/src/OpenFOAM/fields/Fields/Field/FieldM.H b/src/OpenFOAM/fields/Fields/Field/FieldM.H
index 0cb9072bfd..142f83fdce 100644
--- a/src/OpenFOAM/fields/Fields/Field/FieldM.H
+++ b/src/OpenFOAM/fields/Fields/Field/FieldM.H
@@ -33,7 +33,7 @@ Description
 #define Foam_FieldM_H
 
 #include "error.H"
-#include "ListLoopM.H"
+#include "ListLoopM.H"  // For list access macros
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
diff --git a/src/OpenFOAM/containers/Lists/List/ListLoopM.H b/src/OpenFOAM/fields/Fields/Field/ListLoopM.H
similarity index 100%
rename from src/OpenFOAM/containers/Lists/List/ListLoopM.H
rename to src/OpenFOAM/fields/Fields/Field/ListLoopM.H
diff --git a/src/OpenFOAM/primitives/Vector/bools/boolVector.H b/src/OpenFOAM/primitives/Vector/bools/boolVector.H
index baa2e81bb5..f4905a5e2d 100644
--- a/src/OpenFOAM/primitives/Vector/bools/boolVector.H
+++ b/src/OpenFOAM/primitives/Vector/bools/boolVector.H
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2020-2022 OpenCFD Ltd.
+    Copyright (C) 2020-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -65,6 +65,9 @@ public:
         //- Rank of a vector is 1
         static constexpr direction rank = 1;
 
+        //- Number of components in this vector space
+        static constexpr direction nComponents = 3;
+
         //- Component labeling enumeration
         enum components { X, Y, Z };
 
diff --git a/src/OpenFOAM/primitives/direction/direction.H b/src/OpenFOAM/primitives/direction/direction.H
index b9f67e4370..670a3befd6 100644
--- a/src/OpenFOAM/primitives/direction/direction.H
+++ b/src/OpenFOAM/primitives/direction/direction.H
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2020 OpenCFD Ltd.
+    Copyright (C) 2020-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -42,17 +42,20 @@ Note
 #include <cstdint>
 #include <iostream>
 
-#include "pTraits.H"
-
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 namespace Foam
 {
 
-// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+// Forward Declarations
+class Istream;
+class Ostream;
 
+// Typedefs
 typedef uint8_t direction;
 
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
 //- Read direction (uint8_t) from stream.
 direction readDirection(Istream& is);
 
@@ -68,6 +71,10 @@ std::ostream& operator<<(std::ostream& os, const direction val);
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
+#include "pTraits.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
 #endif
 
 // ************************************************************************* //
diff --git a/src/OpenFOAM/primitives/traits/pTraits.H b/src/OpenFOAM/primitives/traits/pTraits.H
index d8e219647f..d5576129f7 100644
--- a/src/OpenFOAM/primitives/traits/pTraits.H
+++ b/src/OpenFOAM/primitives/traits/pTraits.H
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011 OpenFOAM Foundation
-    Copyright (C) 2020-2021 OpenCFD Ltd.
+    Copyright (C) 2020-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -28,10 +28,10 @@ Class
     Foam::pTraits
 
 Description
-    A traits class, which is primarily used for primitives.
+    A traits class, which is primarily used for primitives and vector-space.
 
     All primitives need a specialised version of this class. The
-    specialised version will normally also require a conversion
+    specialised versions will normally also require a conversion
     method.
 
 \*---------------------------------------------------------------------------*/
@@ -39,14 +39,33 @@ Description
 #ifndef Foam_pTraits_H
 #define Foam_pTraits_H
 
+#include "direction.H"
+#include <type_traits>  // For std::integral_constant, std::void_t (C++17)
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace stdFoam
+{
+
+//- Map a sequence of any types to \c void as per C++17 \c std::void_t
+template<class... >
+using void_t = void;
+
+} // End namespace Foam
+
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 namespace Foam
 {
 
-// Forward Declarations
-class Istream;
-class Ostream;
+/*---------------------------------------------------------------------------*\
+                          Class zero_one Declaration
+\*---------------------------------------------------------------------------*/
+
+//- Represents 0/1 range or concept. Used for tagged dispatch or clamping
+class zero_one {};
+
 
 /*---------------------------------------------------------------------------*\
                            Class pTraits Declaration
@@ -78,11 +97,70 @@ public:
 
 
 /*---------------------------------------------------------------------------*\
-                          Class zero_one Declaration
+                              VectorSpace Traits
 \*---------------------------------------------------------------------------*/
 
-//- Represents 0/1 range or concept. Used for tagged dispatch or clamping
-class zero_one {};
+//- Test for VectorSpace : default is false
+template<class T, class = void>
+struct is_vectorspace : std::false_type {};
+
+//- Test for VectorSpace : test for T::rank != 0 static member directly
+//  Do not need pTraits layer since rank is defined via VectorSpace etc
+template<class T>
+struct is_vectorspace<T, stdFoam::void_t<decltype(T::rank)>>
+:
+    std::integral_constant<bool, (T::rank != 0)>
+{};
+
+
+//- The vector-space rank: default is 0.
+template<class T, class = void>
+struct pTraits_rank : std::integral_constant<Foam::direction, 0> {};
+
+//- Rank of VectorSpace,
+//- using the pTraits \c rank static member.
+template<class T>
+struct pTraits_rank
+<
+    T,
+    stdFoam::void_t<decltype(pTraits<T>::rank)>
+>
+:
+    std::integral_constant<Foam::direction, pTraits<T>::rank>
+{};
+
+
+//- The vector-space number of components: default is 1.
+template<class T, class = void>
+struct pTraits_nComponents : std::integral_constant<Foam::direction, 1> {};
+
+//- Number of VectorSpace components,
+//- using the pTraits \c nComponents static member.
+template<class T>
+struct pTraits_nComponents
+<
+    T,
+    stdFoam::void_t<decltype(pTraits<T>::nComponents)>
+>
+:
+    std::integral_constant<Foam::direction, pTraits<T>::nComponents>
+{};
+
+
+//- Test for pTraits zero : default is false
+template<class T, class = void>
+struct pTraits_has_zero : std::false_type {};
+
+//- Test for pTraits zero
+template<class T>
+struct pTraits_has_zero
+<
+    T,
+    stdFoam::void_t<decltype(pTraits<T>::zero)>
+>
+:
+    std::true_type
+{};
 
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //