diff --git a/DDCore/include/DD4hep/detail/Handle.inl b/DDCore/include/DD4hep/detail/Handle.inl
index 44b1eb03f477f18a46a9d6fc1931c1cd35186eec..f33e7370fcdac4a05892e113fd164d2dea06cc12 100644
--- a/DDCore/include/DD4hep/detail/Handle.inl
+++ b/DDCore/include/DD4hep/detail/Handle.inl
@@ -106,19 +106,19 @@ namespace dd4hep {
 #define DD4HEP_HANDLE_PP_NARGS_COUNT() 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, ERROR
 
 // Macros to delegate to concrete, defined-arity implementations:
-#define DD4HEP_HANDLE_XF(count, ...)      DD4HEP_HANDLE_XF_IMPL (count, __VA_ARGS__)
-#define DD4HEP_HANDLE_XF_IMPL(count, ...) DD4HEP_HANDLE_XF_ ## count (__VA_ARGS__)
+#define DD4HEP_HANDLE_VAR_ARG(count, ...)      DD4HEP_HANDLE_VAR_ARG_IMPL (count, __VA_ARGS__)
+#define DD4HEP_HANDLE_VAR_ARG_IMPL(count, ...) DD4HEP_HANDLE_VAR_ARG_ ## count (__VA_ARGS__)
 
-#define DD4HEP_HANDLE_XF_1(CODE,x1)                              DD4HEP_TEMPLATE_HANDLE(CODE,x1)
-#define DD4HEP_HANDLE_XF_2(CODE,x1,x2)                           DD4HEP_IMPLEMENT_SAFE_CAST(x1,x2)  DD4HEP_HANDLE_XF_1(CODE,x1)
-#define DD4HEP_HANDLE_XF_3(CODE,x1,x2,x3)                        DD4HEP_IMPLEMENT_SAFE_CAST(x1,x3)  DD4HEP_HANDLE_XF_2(CODE,x1,x2)
-#define DD4HEP_HANDLE_XF_4(CODE,x1,x2,x3,x4)                     DD4HEP_IMPLEMENT_SAFE_CAST(x1,x4)  DD4HEP_HANDLE_XF_3(CODE,x1,x2,x3)
-#define DD4HEP_HANDLE_XF_5(CODE,x1,x2,x3,x4,x5)                  DD4HEP_IMPLEMENT_SAFE_CAST(x1,x5)  DD4HEP_HANDLE_XF_4(CODE,x1,x2,x3,x4)
-#define DD4HEP_HANDLE_XF_6(CODE,x1,x2,x3,x4,x5,x6)               DD4HEP_IMPLEMENT_SAFE_CAST(x1,x6)  DD4HEP_HANDLE_XF_5(CODE,x1,x2,x3,x4,x5)
-#define DD4HEP_HANDLE_XF_7(CODE,x1,x2,x3,x4,x5,x6,x7)            DD4HEP_IMPLEMENT_SAFE_CAST(x1,x7)  DD4HEP_HANDLE_XF_6(CODE,x1,x2,x3,x4,x5,x6)
-#define DD4HEP_HANDLE_XF_8(CODE,x1,x2,x3,x4,x5,x6,x7,x8)         DD4HEP_IMPLEMENT_SAFE_CAST(x1,x8)  DD4HEP_HANDLE_XF_7(CODE,x1,x2,x3,x4,x5,x6,x7)
-#define DD4HEP_HANDLE_XF_9(CODE,x1,x2,x3,x4,x5,x6,x7,x8,x9)      DD4HEP_IMPLEMENT_SAFE_CAST(x1,x9)  DD4HEP_HANDLE_XF_8(CODE,x1,x2,x3,x4,x5,x6,x7,x8)
-#define DD4HEP_HANDLE_XF_10(CODE,x1,x2,x3,x4,x5,x6,x7,x8,x9,x10) DD4HEP_IMPLEMENT_SAFE_CAST(x1,x10) DD4HEP_HANDLE_XF_9(CODE,x1,x2,x3,x4,x5,x6,x7,x8,x9)
+#define DD4HEP_HANDLE_VAR_ARG_1(CODE,x1)                              DD4HEP_TEMPLATE_HANDLE(CODE,x1)
+#define DD4HEP_HANDLE_VAR_ARG_2(CODE,x1,x2)                           DD4HEP_IMPLEMENT_SAFE_CAST(x1,x2)  DD4HEP_HANDLE_VAR_ARG_1(CODE,x1)
+#define DD4HEP_HANDLE_VAR_ARG_3(CODE,x1,x2,x3)                        DD4HEP_IMPLEMENT_SAFE_CAST(x1,x3)  DD4HEP_HANDLE_VAR_ARG_2(CODE,x1,x2)
+#define DD4HEP_HANDLE_VAR_ARG_4(CODE,x1,x2,x3,x4)                     DD4HEP_IMPLEMENT_SAFE_CAST(x1,x4)  DD4HEP_HANDLE_VAR_ARG_3(CODE,x1,x2,x3)
+#define DD4HEP_HANDLE_VAR_ARG_5(CODE,x1,x2,x3,x4,x5)                  DD4HEP_IMPLEMENT_SAFE_CAST(x1,x5)  DD4HEP_HANDLE_VAR_ARG_4(CODE,x1,x2,x3,x4)
+#define DD4HEP_HANDLE_VAR_ARG_6(CODE,x1,x2,x3,x4,x5,x6)               DD4HEP_IMPLEMENT_SAFE_CAST(x1,x6)  DD4HEP_HANDLE_VAR_ARG_5(CODE,x1,x2,x3,x4,x5)
+#define DD4HEP_HANDLE_VAR_ARG_7(CODE,x1,x2,x3,x4,x5,x6,x7)            DD4HEP_IMPLEMENT_SAFE_CAST(x1,x7)  DD4HEP_HANDLE_VAR_ARG_6(CODE,x1,x2,x3,x4,x5,x6)
+#define DD4HEP_HANDLE_VAR_ARG_8(CODE,x1,x2,x3,x4,x5,x6,x7,x8)         DD4HEP_IMPLEMENT_SAFE_CAST(x1,x8)  DD4HEP_HANDLE_VAR_ARG_7(CODE,x1,x2,x3,x4,x5,x6,x7)
+#define DD4HEP_HANDLE_VAR_ARG_9(CODE,x1,x2,x3,x4,x5,x6,x7,x8,x9)      DD4HEP_IMPLEMENT_SAFE_CAST(x1,x9)  DD4HEP_HANDLE_VAR_ARG_8(CODE,x1,x2,x3,x4,x5,x6,x7,x8)
+#define DD4HEP_HANDLE_VAR_ARG_10(CODE,x1,x2,x3,x4,x5,x6,x7,x8,x9,x10) DD4HEP_IMPLEMENT_SAFE_CAST(x1,x10) DD4HEP_HANDLE_VAR_ARG_9(CODE,x1,x2,x3,x4,x5,x6,x7,x8,x9)
 
 
 #define DD4HEP_TEMPLATE_HANDLE(CODE,X) DD4HEP_TEMPLATE_HANDLE_CODE_##CODE(X) template class dd4hep::Handle<X>
@@ -155,7 +155,7 @@ namespace dd4hep {
   DD4HEP_SAFE_CAST_IMPLEMENTATION(X,X)
 
 // Delegation macro; this is the only macro you need to call from elsewhere:
-#define DD4HEP_INSTANTIATE_HANDLE_CODE(CODE,...)  DD4HEP_HANDLE_XF(DD4HEP_HANDLE_PP_NARGS(__VA_ARGS__),CODE,__VA_ARGS__)
+#define DD4HEP_INSTANTIATE_HANDLE_CODE(CODE,...)  DD4HEP_HANDLE_VAR_ARG(DD4HEP_HANDLE_PP_NARGS(__VA_ARGS__),CODE,__VA_ARGS__)
 #define DD4HEP_INSTANTIATE_HANDLE(...)            DD4HEP_INSTANTIATE_HANDLE_CODE(CAST_ONLY,__VA_ARGS__)
 #define DD4HEP_INSTANTIATE_SHAPE_HANDLE(...)      DD4HEP_INSTANTIATE_HANDLE_CODE(CAST_ONLY,__VA_ARGS__,TGeoShape,TGeoBBox)
 #define DD4HEP_INSTANTIATE_HANDLE_RAW(...)        DD4HEP_INSTANTIATE_HANDLE_CODE(RAW,__VA_ARGS__)