diff --git a/include/xo/procedure2/DPrimitive.hpp b/include/xo/procedure2/DPrimitive.hpp
index 3779831..a5b0125 100644
--- a/include/xo/procedure2/DPrimitive.hpp
+++ b/include/xo/procedure2/DPrimitive.hpp
@@ -75,10 +75,9 @@ namespace xo {
         public:
             using FunctionPtrType = Fn;
             using Traits = detail::PmFnTraits<Fn>;
-
-            //using ACollector = xo::mm::ACollector;
             using AGCObject = xo::mm::AGCObject;
             using AGCObjectVisitor = xo::mm::AGCObjectVisitor;
+            using VisitReason = xo::mm::VisitReason;
             using AAllocator = xo::mm::AAllocator;
             using DArray = xo::scm::DArray;
             using Reflect = xo::reflect::Reflect;
@@ -136,7 +135,7 @@ namespace xo {
             /** @defgroup scm-primitive-gcobject-facet **/
             ///@{
             Primitive * gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept;
-            void visit_gco_children(obj<AGCObjectVisitor> gc) noexcept;
+            void visit_gco_children(VisitReason reason, obj<AGCObjectVisitor> gc) noexcept;
             ///@}
 
         private:
@@ -199,8 +198,9 @@ namespace xo {
 
         template <typename Fn>
         void
-        Primitive<Fn>::visit_gco_children(obj<AGCObjectVisitor> gc) noexcept {
-            gc.visit_poly_child(&type_);
+        Primitive<Fn>::visit_gco_children(xo::mm::VisitReason reason,
+                                          obj<AGCObjectVisitor> gc) noexcept {
+            gc.visit_poly_child(reason, &type_);
             //{
             //    auto e = type_.to_facet<AGCObject>();  // FacetRegistry dep
             //    gc.forward_inplace(e.iface(), (void **)&(type_.data_));
diff --git a/include/xo/procedure2/detail/IGCObject_DPrimitive_gco_0.hpp b/include/xo/procedure2/detail/IGCObject_DPrimitive_gco_0.hpp
index beca085..63986f8 100644
--- a/include/xo/procedure2/detail/IGCObject_DPrimitive_gco_0.hpp
+++ b/include/xo/procedure2/detail/IGCObject_DPrimitive_gco_0.hpp
@@ -45,6 +45,7 @@ namespace xo {
             using AAllocator = xo::mm::AGCObject::AAllocator;
             using ACollector = xo::mm::AGCObject::ACollector;
             using AGCObjectVisitor = xo::mm::AGCObject::AGCObjectVisitor;
+            using VisitReason = xo::mm::AGCObject::VisitReason;
             using Copaque = xo::mm::AGCObject::Copaque;
             using Opaque = xo::mm::AGCObject::Opaque;
             ///@}
@@ -59,7 +60,7 @@ Arguably abusing the word 'visitor' here **/
             /** Invoke fn.visit_child(iface,data) for each child GCObject pointer.
 Context: provides address of data pointer so it can be updated in place
 when @p fn invokes garbage collector reentry point **/
-            static void visit_gco_children(DPrimitive_gco_0 & self, obj<AGCObjectVisitor> fn) noexcept;
+            static void visit_gco_children(DPrimitive_gco_0 & self, VisitReason reason, obj<AGCObjectVisitor> fn) noexcept;
             ///@}
         };
 
diff --git a/include/xo/procedure2/detail/IGCObject_DPrimitive_gco_1_gco.hpp b/include/xo/procedure2/detail/IGCObject_DPrimitive_gco_1_gco.hpp
index 3092e52..c15dedb 100644
--- a/include/xo/procedure2/detail/IGCObject_DPrimitive_gco_1_gco.hpp
+++ b/include/xo/procedure2/detail/IGCObject_DPrimitive_gco_1_gco.hpp
@@ -45,6 +45,7 @@ namespace xo {
             using AAllocator = xo::mm::AGCObject::AAllocator;
             using ACollector = xo::mm::AGCObject::ACollector;
             using AGCObjectVisitor = xo::mm::AGCObject::AGCObjectVisitor;
+            using VisitReason = xo::mm::AGCObject::VisitReason;
             using Copaque = xo::mm::AGCObject::Copaque;
             using Opaque = xo::mm::AGCObject::Opaque;
             ///@}
@@ -59,7 +60,7 @@ Arguably abusing the word 'visitor' here **/
             /** Invoke fn.visit_child(iface,data) for each child GCObject pointer.
 Context: provides address of data pointer so it can be updated in place
 when @p fn invokes garbage collector reentry point **/
-            static void visit_gco_children(DPrimitive_gco_1_gco & self, obj<AGCObjectVisitor> fn) noexcept;
+            static void visit_gco_children(DPrimitive_gco_1_gco & self, VisitReason reason, obj<AGCObjectVisitor> fn) noexcept;
             ///@}
         };
 
diff --git a/include/xo/procedure2/detail/IGCObject_DPrimitive_gco_2_dict_string.hpp b/include/xo/procedure2/detail/IGCObject_DPrimitive_gco_2_dict_string.hpp
index 1fca4b6..6cc1754 100644
--- a/include/xo/procedure2/detail/IGCObject_DPrimitive_gco_2_dict_string.hpp
+++ b/include/xo/procedure2/detail/IGCObject_DPrimitive_gco_2_dict_string.hpp
@@ -45,6 +45,7 @@ namespace xo {
             using AAllocator = xo::mm::AGCObject::AAllocator;
             using ACollector = xo::mm::AGCObject::ACollector;
             using AGCObjectVisitor = xo::mm::AGCObject::AGCObjectVisitor;
+            using VisitReason = xo::mm::AGCObject::VisitReason;
             using Copaque = xo::mm::AGCObject::Copaque;
             using Opaque = xo::mm::AGCObject::Opaque;
             ///@}
@@ -59,7 +60,7 @@ Arguably abusing the word 'visitor' here **/
             /** Invoke fn.visit_child(iface,data) for each child GCObject pointer.
 Context: provides address of data pointer so it can be updated in place
 when @p fn invokes garbage collector reentry point **/
-            static void visit_gco_children(DPrimitive_gco_2_dict_string & self, obj<AGCObjectVisitor> fn) noexcept;
+            static void visit_gco_children(DPrimitive_gco_2_dict_string & self, VisitReason reason, obj<AGCObjectVisitor> fn) noexcept;
             ///@}
         };
 
diff --git a/include/xo/procedure2/detail/IGCObject_DPrimitive_gco_2_gco_gco.hpp b/include/xo/procedure2/detail/IGCObject_DPrimitive_gco_2_gco_gco.hpp
index 14e66c3..52c46f4 100644
--- a/include/xo/procedure2/detail/IGCObject_DPrimitive_gco_2_gco_gco.hpp
+++ b/include/xo/procedure2/detail/IGCObject_DPrimitive_gco_2_gco_gco.hpp
@@ -45,6 +45,7 @@ namespace xo {
             using AAllocator = xo::mm::AGCObject::AAllocator;
             using ACollector = xo::mm::AGCObject::ACollector;
             using AGCObjectVisitor = xo::mm::AGCObject::AGCObjectVisitor;
+            using VisitReason = xo::mm::AGCObject::VisitReason;
             using Copaque = xo::mm::AGCObject::Copaque;
             using Opaque = xo::mm::AGCObject::Opaque;
             ///@}
@@ -59,7 +60,7 @@ Arguably abusing the word 'visitor' here **/
             /** Invoke fn.visit_child(iface,data) for each child GCObject pointer.
 Context: provides address of data pointer so it can be updated in place
 when @p fn invokes garbage collector reentry point **/
-            static void visit_gco_children(DPrimitive_gco_2_gco_gco & self, obj<AGCObjectVisitor> fn) noexcept;
+            static void visit_gco_children(DPrimitive_gco_2_gco_gco & self, VisitReason reason, obj<AGCObjectVisitor> fn) noexcept;
             ///@}
         };
 
diff --git a/include/xo/procedure2/detail/IGCObject_DPrimitive_gco_3_dict_string_gco.hpp b/include/xo/procedure2/detail/IGCObject_DPrimitive_gco_3_dict_string_gco.hpp
index 994682c..cc8294e 100644
--- a/include/xo/procedure2/detail/IGCObject_DPrimitive_gco_3_dict_string_gco.hpp
+++ b/include/xo/procedure2/detail/IGCObject_DPrimitive_gco_3_dict_string_gco.hpp
@@ -45,6 +45,7 @@ namespace xo {
             using AAllocator = xo::mm::AGCObject::AAllocator;
             using ACollector = xo::mm::AGCObject::ACollector;
             using AGCObjectVisitor = xo::mm::AGCObject::AGCObjectVisitor;
+            using VisitReason = xo::mm::AGCObject::VisitReason;
             using Copaque = xo::mm::AGCObject::Copaque;
             using Opaque = xo::mm::AGCObject::Opaque;
             ///@}
@@ -59,7 +60,7 @@ Arguably abusing the word 'visitor' here **/
             /** Invoke fn.visit_child(iface,data) for each child GCObject pointer.
 Context: provides address of data pointer so it can be updated in place
 when @p fn invokes garbage collector reentry point **/
-            static void visit_gco_children(DPrimitive_gco_3_dict_string_gco & self, obj<AGCObjectVisitor> fn) noexcept;
+            static void visit_gco_children(DPrimitive_gco_3_dict_string_gco & self, VisitReason reason, obj<AGCObjectVisitor> fn) noexcept;
             ///@}
         };
 
diff --git a/src/procedure2/facet/IGCObject_DPrimitive_gco_0.cpp b/src/procedure2/facet/IGCObject_DPrimitive_gco_0.cpp
index 150adfd..80b04c1 100644
--- a/src/procedure2/facet/IGCObject_DPrimitive_gco_0.cpp
+++ b/src/procedure2/facet/IGCObject_DPrimitive_gco_0.cpp
@@ -21,9 +21,9 @@ namespace xo {
             return self.gco_shallow_move(gc);
         }
         auto
-        IGCObject_DPrimitive_gco_0::visit_gco_children(DPrimitive_gco_0 & self, obj<AGCObjectVisitor> fn) noexcept -> void
+        IGCObject_DPrimitive_gco_0::visit_gco_children(DPrimitive_gco_0 & self, VisitReason reason, obj<AGCObjectVisitor> fn) noexcept -> void
         {
-            self.visit_gco_children(fn);
+            self.visit_gco_children(reason, fn);
         }
 
     } /*namespace scm*/
diff --git a/src/procedure2/facet/IGCObject_DPrimitive_gco_1_gco.cpp b/src/procedure2/facet/IGCObject_DPrimitive_gco_1_gco.cpp
index 202389d..865cd64 100644
--- a/src/procedure2/facet/IGCObject_DPrimitive_gco_1_gco.cpp
+++ b/src/procedure2/facet/IGCObject_DPrimitive_gco_1_gco.cpp
@@ -21,9 +21,9 @@ namespace xo {
             return self.gco_shallow_move(gc);
         }
         auto
-        IGCObject_DPrimitive_gco_1_gco::visit_gco_children(DPrimitive_gco_1_gco & self, obj<AGCObjectVisitor> fn) noexcept -> void
+        IGCObject_DPrimitive_gco_1_gco::visit_gco_children(DPrimitive_gco_1_gco & self, VisitReason reason, obj<AGCObjectVisitor> fn) noexcept -> void
         {
-            self.visit_gco_children(fn);
+            self.visit_gco_children(reason, fn);
         }
 
     } /*namespace scm*/
diff --git a/src/procedure2/facet/IGCObject_DPrimitive_gco_2_dict_string.cpp b/src/procedure2/facet/IGCObject_DPrimitive_gco_2_dict_string.cpp
index c9b4717..5e9bbcb 100644
--- a/src/procedure2/facet/IGCObject_DPrimitive_gco_2_dict_string.cpp
+++ b/src/procedure2/facet/IGCObject_DPrimitive_gco_2_dict_string.cpp
@@ -21,9 +21,9 @@ namespace xo {
             return self.gco_shallow_move(gc);
         }
         auto
-        IGCObject_DPrimitive_gco_2_dict_string::visit_gco_children(DPrimitive_gco_2_dict_string & self, obj<AGCObjectVisitor> fn) noexcept -> void
+        IGCObject_DPrimitive_gco_2_dict_string::visit_gco_children(DPrimitive_gco_2_dict_string & self, VisitReason reason, obj<AGCObjectVisitor> fn) noexcept -> void
         {
-            self.visit_gco_children(fn);
+            self.visit_gco_children(reason, fn);
         }
 
     } /*namespace scm*/
diff --git a/src/procedure2/facet/IGCObject_DPrimitive_gco_2_gco_gco.cpp b/src/procedure2/facet/IGCObject_DPrimitive_gco_2_gco_gco.cpp
index 65851b1..ef410d8 100644
--- a/src/procedure2/facet/IGCObject_DPrimitive_gco_2_gco_gco.cpp
+++ b/src/procedure2/facet/IGCObject_DPrimitive_gco_2_gco_gco.cpp
@@ -21,9 +21,9 @@ namespace xo {
             return self.gco_shallow_move(gc);
         }
         auto
-        IGCObject_DPrimitive_gco_2_gco_gco::visit_gco_children(DPrimitive_gco_2_gco_gco & self, obj<AGCObjectVisitor> fn) noexcept -> void
+        IGCObject_DPrimitive_gco_2_gco_gco::visit_gco_children(DPrimitive_gco_2_gco_gco & self, VisitReason reason, obj<AGCObjectVisitor> fn) noexcept -> void
         {
-            self.visit_gco_children(fn);
+            self.visit_gco_children(reason, fn);
         }
 
     } /*namespace scm*/
diff --git a/src/procedure2/facet/IGCObject_DPrimitive_gco_3_dict_string_gco.cpp b/src/procedure2/facet/IGCObject_DPrimitive_gco_3_dict_string_gco.cpp
index 89be54a..58e26de 100644
--- a/src/procedure2/facet/IGCObject_DPrimitive_gco_3_dict_string_gco.cpp
+++ b/src/procedure2/facet/IGCObject_DPrimitive_gco_3_dict_string_gco.cpp
@@ -21,9 +21,9 @@ namespace xo {
             return self.gco_shallow_move(gc);
         }
         auto
-        IGCObject_DPrimitive_gco_3_dict_string_gco::visit_gco_children(DPrimitive_gco_3_dict_string_gco & self, obj<AGCObjectVisitor> fn) noexcept -> void
+        IGCObject_DPrimitive_gco_3_dict_string_gco::visit_gco_children(DPrimitive_gco_3_dict_string_gco & self, VisitReason reason, obj<AGCObjectVisitor> fn) noexcept -> void
         {
-            self.visit_gco_children(fn);
+            self.visit_gco_children(reason, fn);
         }
 
     } /*namespace scm*/