diff --git a/include/xo/stringtable2/DString.hpp b/include/xo/stringtable2/DString.hpp
index 7d736a3..73e165d 100644
--- a/include/xo/stringtable2/DString.hpp
+++ b/include/xo/stringtable2/DString.hpp
@@ -50,6 +50,8 @@ namespace xo {
             //using ACollector = xo::mm::ACollector;
             /** object visitor (garbage collector proxy) **/
             using AGCObjectVisitor = xo::mm::AGCObjectVisitor;
+            /** visitor hint **/
+            using VisitReason = xo::mm::VisitReason;
             /** ppindentinfo for APrintable **/
             using ppindentinfo = xo::print::ppindentinfo;
             ///@}
@@ -251,7 +253,7 @@ namespace xo {
             /** fixup child pointers (trivial for DString, no children)
              *  note: cref so we can use forward decl
              **/
-            void visit_gco_children(obj<AGCObjectVisitor> gc) noexcept;
+            void visit_gco_children(VisitReason reason, obj<AGCObjectVisitor> gc) noexcept;
 
             ///@}
 
diff --git a/include/xo/stringtable2/DUniqueString.hpp b/include/xo/stringtable2/DUniqueString.hpp
index 27a364e..fedf669 100644
--- a/include/xo/stringtable2/DUniqueString.hpp
+++ b/include/xo/stringtable2/DUniqueString.hpp
@@ -28,6 +28,7 @@ namespace xo {
             using AAllocator = xo::mm::AAllocator;
             using ACollector = xo::mm::ACollector;
             using AGCObjectVisitor = xo::mm::AGCObjectVisitor;
+            using VisitReason = xo::mm::VisitReason;
             using size_type = DString::size_type;
             using ppindentinfo = xo::print::ppindentinfo;
 
@@ -93,7 +94,7 @@ namespace xo {
             DUniqueString * gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept;
 
             /** fixup child pointers (trivial for DUniqueString, no gc-owned children **/
-            void visit_gco_children(obj<AGCObjectVisitor> gc) noexcept;
+            void visit_gco_children(VisitReason reason, obj<AGCObjectVisitor> gc) noexcept;
 
             ///@}
 
diff --git a/include/xo/stringtable2/string/IGCObject_DString.hpp b/include/xo/stringtable2/string/IGCObject_DString.hpp
index f35b0a5..e9c15f4 100644
--- a/include/xo/stringtable2/string/IGCObject_DString.hpp
+++ b/include/xo/stringtable2/string/IGCObject_DString.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(DString & self, obj<AGCObjectVisitor> fn) noexcept;
+            static void visit_gco_children(DString & self, VisitReason reason, obj<AGCObjectVisitor> fn) noexcept;
             ///@}
         };
 
diff --git a/include/xo/stringtable2/uniquestring/IGCObject_DUniqueString.hpp b/include/xo/stringtable2/uniquestring/IGCObject_DUniqueString.hpp
index 5771e05..77c0ea6 100644
--- a/include/xo/stringtable2/uniquestring/IGCObject_DUniqueString.hpp
+++ b/include/xo/stringtable2/uniquestring/IGCObject_DUniqueString.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(DUniqueString & self, obj<AGCObjectVisitor> fn) noexcept;
+            static void visit_gco_children(DUniqueString & self, VisitReason reason, obj<AGCObjectVisitor> fn) noexcept;
             ///@}
         };
 
diff --git a/src/stringtable2/DString.cpp b/src/stringtable2/DString.cpp
index 1b9ce48..30bfb39 100644
--- a/src/stringtable2/DString.cpp
+++ b/src/stringtable2/DString.cpp
@@ -167,7 +167,7 @@ namespace xo {
         }
 
         void
-        DString::visit_gco_children(obj<AGCObjectVisitor>) noexcept
+        DString::visit_gco_children(VisitReason, obj<AGCObjectVisitor>) noexcept
         {
             // no-op.  no children!
         }
diff --git a/src/stringtable2/DUniqueString.cpp b/src/stringtable2/DUniqueString.cpp
index 98371ad..bc63cf0 100644
--- a/src/stringtable2/DUniqueString.cpp
+++ b/src/stringtable2/DUniqueString.cpp
@@ -109,7 +109,7 @@ namespace xo {
         }
 
         void
-        DUniqueString::visit_gco_children(obj<AGCObjectVisitor>) noexcept
+        DUniqueString::visit_gco_children(VisitReason, obj<AGCObjectVisitor>) noexcept
         {
             // no-op -- childless!
         }
diff --git a/src/stringtable2/IGCObject_DString.cpp b/src/stringtable2/IGCObject_DString.cpp
index 716c043..a3a384b 100644
--- a/src/stringtable2/IGCObject_DString.cpp
+++ b/src/stringtable2/IGCObject_DString.cpp
@@ -21,9 +21,9 @@ namespace xo {
             return self.gco_shallow_move(gc);
         }
         auto
-        IGCObject_DString::visit_gco_children(DString & self, obj<AGCObjectVisitor> fn) noexcept -> void
+        IGCObject_DString::visit_gco_children(DString & 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/stringtable2/IGCObject_DUniqueString.cpp b/src/stringtable2/IGCObject_DUniqueString.cpp
index e43fc8b..88fbaaa 100644
--- a/src/stringtable2/IGCObject_DUniqueString.cpp
+++ b/src/stringtable2/IGCObject_DUniqueString.cpp
@@ -21,9 +21,9 @@ namespace xo {
             return self.gco_shallow_move(gc);
         }
         auto
-        IGCObject_DUniqueString::visit_gco_children(DUniqueString & self, obj<AGCObjectVisitor> fn) noexcept -> void
+        IGCObject_DUniqueString::visit_gco_children(DUniqueString & self, VisitReason reason, obj<AGCObjectVisitor> fn) noexcept -> void
         {
-            self.visit_gco_children(fn);
+            self.visit_gco_children(reason, fn);
         }
 
     } /*namespace scm*/