diff --git a/include/xo/object2/DArray.hpp b/include/xo/object2/DArray.hpp
index 71c7f44..cd2bab2 100644
--- a/include/xo/object2/DArray.hpp
+++ b/include/xo/object2/DArray.hpp
@@ -6,7 +6,7 @@
 #pragma once
 
 #include <xo/alloc2/GCObject.hpp>
-#include <xo/alloc2/Collector.hpp>
+//#include <xo/alloc2/Collector.hpp>
 #include <xo/alloc2/Allocator.hpp>
 #include <xo/facet/obj.hpp>
 #include <xo/indentlog/print/ppindentinfo.hpp>
@@ -33,7 +33,7 @@ namespace xo {
             /** xo allocator facet **/
             using AAllocator = xo::mm::AAllocator;
             /** garbage collector facet **/
-            using ACollector = xo::mm::ACollector;
+            //using ACollector = xo::mm::ACollector;
             /** gc-aware object facet **/
             using AGCObject = xo::mm::AGCObject;
             /** gc-centric object visitor **/
@@ -148,7 +148,7 @@ namespace xo {
             /** @defgroup darray-gcobject-methods **/
             ///@{
             /** move to new address, mandated by @p gc **/
-            DArray * shallow_move(obj<ACollector> gc) noexcept;
+            DArray * gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept;
             /** forward elements to @p gc to-space; replace originals with forarding pointers **/
             void visit_gco_children(obj<AGCObjectVisitor> gc) noexcept;
             ///@}
diff --git a/include/xo/object2/DBoolean.hpp b/include/xo/object2/DBoolean.hpp
index 1637bc7..53ee4b8 100644
--- a/include/xo/object2/DBoolean.hpp
+++ b/include/xo/object2/DBoolean.hpp
@@ -5,7 +5,7 @@
 
 #pragma once
 
-#include <xo/alloc2/Collector.hpp>
+//#include <xo/alloc2/Collector.hpp>
 #include <xo/alloc2/Allocator.hpp>
 #include <xo/alloc2/GCObjectVisitor.hpp>
 #include <xo/indentlog/print/ppindentinfo.hpp>
@@ -16,7 +16,7 @@ namespace xo {
     namespace scm {
         struct DBoolean {
             using AAllocator = xo::mm::AAllocator;
-            using ACollector = xo::mm::ACollector;
+            //using ACollector = xo::mm::ACollector;
             using AGCObjectVisitor = xo::mm::AGCObjectVisitor;
             using AGCObject = xo::mm::AGCObject;
             using ppindentinfo = xo::print::ppindentinfo;
@@ -39,7 +39,7 @@ namespace xo {
 
             // GCObject facet
 
-            DBoolean * shallow_move(obj<ACollector> gc) noexcept;
+            DBoolean * gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept;
             void visit_gco_children(obj<AGCObjectVisitor> gc) noexcept;
 
         private:
diff --git a/include/xo/object2/DDictionary.hpp b/include/xo/object2/DDictionary.hpp
index 9ab75be..cda1d6f 100644
--- a/include/xo/object2/DDictionary.hpp
+++ b/include/xo/object2/DDictionary.hpp
@@ -204,7 +204,7 @@ namespace xo {
             /** @defgroup ddictionary-gcobject-methods **/
             ///@{
             /** return shallow copy of this array, using memory from @p mm **/
-            DDictionary * shallow_move(obj<ACollector> gc) noexcept;
+            DDictionary * gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept;
             /** forward elements to @p gc to-space; replace originals with forwarding pointers **/
             void visit_gco_children(obj<AGCObjectVisitor> gc) noexcept;
             ///@}
diff --git a/include/xo/object2/DFloat.hpp b/include/xo/object2/DFloat.hpp
index 9532204..edd4f1e 100644
--- a/include/xo/object2/DFloat.hpp
+++ b/include/xo/object2/DFloat.hpp
@@ -6,7 +6,7 @@
 #pragma once
 
 #include <xo/alloc2/Allocator.hpp>
-#include <xo/alloc2/Collector.hpp>
+//#include <xo/alloc2/Collector.hpp>
 #include <xo/alloc2/GCObjectVisitor.hpp>
 #include <xo/facet/obj.hpp>
 #include <xo/indentlog/print/ppindentinfo.hpp>
@@ -15,7 +15,7 @@ namespace xo {
     namespace scm {
         struct DFloat {
             using AAllocator = xo::mm::AAllocator;
-            using ACollector = xo::mm::ACollector;
+            //using ACollector = xo::mm::ACollector;
             using AGCObjectVisitor = xo::mm::AGCObjectVisitor;
             using ppindentinfo = xo::print::ppindentinfo;
             using value_type = double;
@@ -36,7 +36,7 @@ namespace xo {
             bool pretty(const ppindentinfo & ppii) const;
 
             // GCObject facet
-            DFloat * shallow_move(obj<ACollector> gc) noexcept;
+            DFloat * gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept;
             void visit_gco_children(obj<AGCObjectVisitor> gc) noexcept;
 
         private:
diff --git a/include/xo/object2/DInteger.hpp b/include/xo/object2/DInteger.hpp
index 4b0552b..d82d989 100644
--- a/include/xo/object2/DInteger.hpp
+++ b/include/xo/object2/DInteger.hpp
@@ -5,7 +5,7 @@
 
 #pragma once
 
-#include <xo/alloc2/Collector.hpp>
+//#include <xo/alloc2/Collector.hpp>
 #include <xo/alloc2/GCObjectVisitor.hpp>
 #include <xo/alloc2/Allocator.hpp>
 #include <xo/indentlog/print/ppindentinfo.hpp>
@@ -16,7 +16,7 @@ namespace xo {
     namespace scm {
         struct DInteger {
             using AAllocator = xo::mm::AAllocator;
-            using ACollector = xo::mm::ACollector;
+            //using ACollector = xo::mm::ACollector;
             using AGCObjectVisitor = xo::mm::AGCObjectVisitor;
             using AGCObject = xo::mm::AGCObject;
             using ppindentinfo = xo::print::ppindentinfo;
@@ -41,7 +41,7 @@ namespace xo {
 
             // GCObject facet
 
-            DInteger * shallow_move(obj<ACollector> gc) noexcept;
+            DInteger * gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept;
             void visit_gco_children(obj<AGCObjectVisitor> gc) noexcept;
 
         private:
diff --git a/include/xo/object2/DList.hpp b/include/xo/object2/DList.hpp
index e694acb..da21ca4 100644
--- a/include/xo/object2/DList.hpp
+++ b/include/xo/object2/DList.hpp
@@ -5,6 +5,7 @@
 
 #pragma once
 
+#include <xo/alloc2/Collector.hpp>
 #include <xo/alloc2/GCObject.hpp>
 #include <xo/facet/obj.hpp>
 #include <xo/indentlog/print/ppindentinfo.hpp>
@@ -70,7 +71,7 @@ namespace xo {
 
             /** @defgroup xo-scm-list-gcobject-facet gcobject facet **/
             ///@{
-            DList * shallow_move(obj<ACollector> gc) noexcept;
+            DList * gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept;
             void visit_gco_children(obj<AGCObjectVisitor> gc) noexcept;
             ///@}
 
diff --git a/include/xo/object2/DRuntimeError.hpp b/include/xo/object2/DRuntimeError.hpp
index 782185b..43fe4a0 100644
--- a/include/xo/object2/DRuntimeError.hpp
+++ b/include/xo/object2/DRuntimeError.hpp
@@ -17,7 +17,7 @@ namespace xo {
         class DRuntimeError {
         public:
             using AGCObject = xo::mm::AGCObject;
-            using ACollector = xo::mm::ACollector;
+            //using ACollector = xo::mm::ACollector;
             using AGCObjectVisitor = xo::mm::AGCObjectVisitor;
             using AAllocator = xo::mm::AAllocator;
             using ppindentinfo = xo::print::ppindentinfo;
@@ -50,7 +50,7 @@ namespace xo {
             /** @defgroup scm-runtimeerror-gcobject-facet gcobject facet **/
             ///@{
 
-            DRuntimeError * shallow_move(obj<ACollector> gc) noexcept;
+            DRuntimeError * gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept;
             void visit_gco_children(obj<AGCObjectVisitor> gc) noexcept;
 
             ///@}
diff --git a/include/xo/object2/array/IGCObject_DArray.hpp b/include/xo/object2/array/IGCObject_DArray.hpp
index bb326f0..75399cf 100644
--- a/include/xo/object2/array/IGCObject_DArray.hpp
+++ b/include/xo/object2/array/IGCObject_DArray.hpp
@@ -51,8 +51,9 @@ namespace xo {
             // const methods
 
             // non-const methods
-            /** move instance using collector **/
-            static Opaque shallow_move(DArray & self, obj<ACollector> gc) noexcept;
+            /** move instance using object visitor.
+Arguably abusing the word 'visitor' here **/
+            static Opaque gco_shallow_move(DArray & self, obj<AGCObjectVisitor> gc) noexcept;
             /** 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 **/
diff --git a/include/xo/object2/boolean/IGCObject_DBoolean.hpp b/include/xo/object2/boolean/IGCObject_DBoolean.hpp
index 9ad6643..30fc70f 100644
--- a/include/xo/object2/boolean/IGCObject_DBoolean.hpp
+++ b/include/xo/object2/boolean/IGCObject_DBoolean.hpp
@@ -51,8 +51,9 @@ namespace xo {
             // const methods
 
             // non-const methods
-            /** move instance using collector **/
-            static Opaque shallow_move(DBoolean & self, obj<ACollector> gc) noexcept;
+            /** move instance using object visitor.
+Arguably abusing the word 'visitor' here **/
+            static Opaque gco_shallow_move(DBoolean & self, obj<AGCObjectVisitor> gc) noexcept;
             /** 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 **/
diff --git a/include/xo/object2/dictionary/IGCObject_DDictionary.hpp b/include/xo/object2/dictionary/IGCObject_DDictionary.hpp
index d389bf6..5d45179 100644
--- a/include/xo/object2/dictionary/IGCObject_DDictionary.hpp
+++ b/include/xo/object2/dictionary/IGCObject_DDictionary.hpp
@@ -51,8 +51,9 @@ namespace xo {
             // const methods
 
             // non-const methods
-            /** move instance using collector **/
-            static Opaque shallow_move(DDictionary & self, obj<ACollector> gc) noexcept;
+            /** move instance using object visitor.
+Arguably abusing the word 'visitor' here **/
+            static Opaque gco_shallow_move(DDictionary & self, obj<AGCObjectVisitor> gc) noexcept;
             /** 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 **/
diff --git a/include/xo/object2/error/IGCObject_DRuntimeError.hpp b/include/xo/object2/error/IGCObject_DRuntimeError.hpp
index 1b2a822..a0039ad 100644
--- a/include/xo/object2/error/IGCObject_DRuntimeError.hpp
+++ b/include/xo/object2/error/IGCObject_DRuntimeError.hpp
@@ -51,8 +51,9 @@ namespace xo {
             // const methods
 
             // non-const methods
-            /** move instance using collector **/
-            static Opaque shallow_move(DRuntimeError & self, obj<ACollector> gc) noexcept;
+            /** move instance using object visitor.
+Arguably abusing the word 'visitor' here **/
+            static Opaque gco_shallow_move(DRuntimeError & self, obj<AGCObjectVisitor> gc) noexcept;
             /** 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 **/
diff --git a/include/xo/object2/list/IGCObject_DList.hpp b/include/xo/object2/list/IGCObject_DList.hpp
index dcc8638..4002106 100644
--- a/include/xo/object2/list/IGCObject_DList.hpp
+++ b/include/xo/object2/list/IGCObject_DList.hpp
@@ -51,8 +51,9 @@ namespace xo {
             // const methods
 
             // non-const methods
-            /** move instance using collector **/
-            static Opaque shallow_move(DList & self, obj<ACollector> gc) noexcept;
+            /** move instance using object visitor.
+Arguably abusing the word 'visitor' here **/
+            static Opaque gco_shallow_move(DList & self, obj<AGCObjectVisitor> gc) noexcept;
             /** 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 **/
diff --git a/include/xo/object2/number/IGCObject_DFloat.hpp b/include/xo/object2/number/IGCObject_DFloat.hpp
index 3cb453e..eb50bb3 100644
--- a/include/xo/object2/number/IGCObject_DFloat.hpp
+++ b/include/xo/object2/number/IGCObject_DFloat.hpp
@@ -52,8 +52,9 @@ namespace xo {
             // const methods
 
             // non-const methods
-            /** move instance using collector **/
-            static Opaque shallow_move(DFloat & self, obj<ACollector> gc) noexcept;
+            /** move instance using object visitor.
+Arguably abusing the word 'visitor' here **/
+            static Opaque gco_shallow_move(DFloat & self, obj<AGCObjectVisitor> gc) noexcept;
             /** 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 **/
diff --git a/include/xo/object2/number/IGCObject_DInteger.hpp b/include/xo/object2/number/IGCObject_DInteger.hpp
index 9e7450f..fece77f 100644
--- a/include/xo/object2/number/IGCObject_DInteger.hpp
+++ b/include/xo/object2/number/IGCObject_DInteger.hpp
@@ -51,8 +51,9 @@ namespace xo {
             // const methods
 
             // non-const methods
-            /** move instance using collector **/
-            static Opaque shallow_move(DInteger & self, obj<ACollector> gc) noexcept;
+            /** move instance using object visitor.
+Arguably abusing the word 'visitor' here **/
+            static Opaque gco_shallow_move(DInteger & self, obj<AGCObjectVisitor> gc) noexcept;
             /** 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 **/
diff --git a/src/object2/DArray.cpp b/src/object2/DArray.cpp
index a365810..f6c16b7 100644
--- a/src/object2/DArray.cpp
+++ b/src/object2/DArray.cpp
@@ -175,7 +175,7 @@ namespace xo {
         // gc hooks for IGCObject_DArray
 
         DArray *
-        DArray::shallow_move(obj<ACollector> gc) noexcept
+        DArray::gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept
         {
             // note: not using gc.std_move_for() here.
             //       flexible array -> compiler doesn't know actual DArray allocation size
diff --git a/src/object2/DBoolean.cpp b/src/object2/DBoolean.cpp
index d2c2b7c..5d2de40 100644
--- a/src/object2/DBoolean.cpp
+++ b/src/object2/DBoolean.cpp
@@ -30,7 +30,7 @@ namespace xo {
         }
 
         DBoolean *
-        DBoolean::shallow_move(obj<ACollector> gc) noexcept
+        DBoolean::gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept
         {
             return gc.std_move_for(this);
         }
diff --git a/src/object2/DDictionary.cpp b/src/object2/DDictionary.cpp
index 63e0e9e..f7806b6 100644
--- a/src/object2/DDictionary.cpp
+++ b/src/object2/DDictionary.cpp
@@ -268,7 +268,7 @@ namespace xo {
         // ----- gcobject facet -----
 
         DDictionary *
-        DDictionary::shallow_move(obj<ACollector> gc) noexcept
+        DDictionary::gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept
         {
             return gc.std_move_for(this);
         }
diff --git a/src/object2/DFloat.cpp b/src/object2/DFloat.cpp
index 3515dcf..99d8b23 100644
--- a/src/object2/DFloat.cpp
+++ b/src/object2/DFloat.cpp
@@ -28,7 +28,7 @@ namespace xo {
         }
 
         DFloat *
-        DFloat::shallow_move(obj<ACollector> gc) noexcept
+        DFloat::gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept
         {
             return gc.std_move_for(this);
         }
diff --git a/src/object2/DInteger.cpp b/src/object2/DInteger.cpp
index b73391c..1c17d9c 100644
--- a/src/object2/DInteger.cpp
+++ b/src/object2/DInteger.cpp
@@ -28,7 +28,7 @@ namespace xo {
         }
 
         DInteger *
-        DInteger::shallow_move(obj<ACollector> gc) noexcept
+        DInteger::gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept
         {
             return gc.std_move_for(this);
         }
diff --git a/src/object2/DList.cpp b/src/object2/DList.cpp
index 5670118..fc2070f 100644
--- a/src/object2/DList.cpp
+++ b/src/object2/DList.cpp
@@ -179,7 +179,7 @@ namespace xo {
         // ----- GCObject facet ------
 
         DList *
-        DList::shallow_move(obj<ACollector> gc) noexcept
+        DList::gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept
         {
             return gc.std_move_for(this);
         }
diff --git a/src/object2/DRuntimeError.cpp b/src/object2/DRuntimeError.cpp
index d46dcb2..7edb622 100644
--- a/src/object2/DRuntimeError.cpp
+++ b/src/object2/DRuntimeError.cpp
@@ -53,7 +53,7 @@ namespace xo {
         // ----- GCObject facet -----
 
         DRuntimeError *
-        DRuntimeError::shallow_move(obj<ACollector> gc) noexcept
+        DRuntimeError::gco_shallow_move(obj<AGCObjectVisitor> gc) noexcept
         {
             return gc.std_move_for(this);
         }
diff --git a/src/object2/IGCObject_DArray.cpp b/src/object2/IGCObject_DArray.cpp
index 38a3197..6de8b94 100644
--- a/src/object2/IGCObject_DArray.cpp
+++ b/src/object2/IGCObject_DArray.cpp
@@ -16,9 +16,9 @@
 namespace xo {
     namespace scm {
         auto
-        IGCObject_DArray::shallow_move(DArray & self, obj<ACollector> gc) noexcept -> Opaque
+        IGCObject_DArray::gco_shallow_move(DArray & self, obj<AGCObjectVisitor> gc) noexcept -> Opaque
         {
-            return self.shallow_move(gc);
+            return self.gco_shallow_move(gc);
         }
         auto
         IGCObject_DArray::visit_gco_children(DArray & self, obj<AGCObjectVisitor> fn) noexcept -> void
diff --git a/src/object2/IGCObject_DBoolean.cpp b/src/object2/IGCObject_DBoolean.cpp
index d76460d..d791116 100644
--- a/src/object2/IGCObject_DBoolean.cpp
+++ b/src/object2/IGCObject_DBoolean.cpp
@@ -16,9 +16,9 @@
 namespace xo {
     namespace scm {
         auto
-        IGCObject_DBoolean::shallow_move(DBoolean & self, obj<ACollector> gc) noexcept -> Opaque
+        IGCObject_DBoolean::gco_shallow_move(DBoolean & self, obj<AGCObjectVisitor> gc) noexcept -> Opaque
         {
-            return self.shallow_move(gc);
+            return self.gco_shallow_move(gc);
         }
         auto
         IGCObject_DBoolean::visit_gco_children(DBoolean & self, obj<AGCObjectVisitor> fn) noexcept -> void
diff --git a/src/object2/IGCObject_DDictionary.cpp b/src/object2/IGCObject_DDictionary.cpp
index cd011b1..41d462c 100644
--- a/src/object2/IGCObject_DDictionary.cpp
+++ b/src/object2/IGCObject_DDictionary.cpp
@@ -16,9 +16,9 @@
 namespace xo {
     namespace scm {
         auto
-        IGCObject_DDictionary::shallow_move(DDictionary & self, obj<ACollector> gc) noexcept -> Opaque
+        IGCObject_DDictionary::gco_shallow_move(DDictionary & self, obj<AGCObjectVisitor> gc) noexcept -> Opaque
         {
-            return self.shallow_move(gc);
+            return self.gco_shallow_move(gc);
         }
         auto
         IGCObject_DDictionary::visit_gco_children(DDictionary & self, obj<AGCObjectVisitor> fn) noexcept -> void
diff --git a/src/object2/IGCObject_DFloat.cpp b/src/object2/IGCObject_DFloat.cpp
index ab58f84..adcb994 100644
--- a/src/object2/IGCObject_DFloat.cpp
+++ b/src/object2/IGCObject_DFloat.cpp
@@ -16,9 +16,9 @@
 namespace xo {
     namespace scm {
         auto
-        IGCObject_DFloat::shallow_move(DFloat & self, obj<ACollector> gc) noexcept -> Opaque
+        IGCObject_DFloat::gco_shallow_move(DFloat & self, obj<AGCObjectVisitor> gc) noexcept -> Opaque
         {
-            return self.shallow_move(gc);
+            return self.gco_shallow_move(gc);
         }
         auto
         IGCObject_DFloat::visit_gco_children(DFloat & self, obj<AGCObjectVisitor> fn) noexcept -> void
diff --git a/src/object2/IGCObject_DInteger.cpp b/src/object2/IGCObject_DInteger.cpp
index 13ea837..b4b57fc 100644
--- a/src/object2/IGCObject_DInteger.cpp
+++ b/src/object2/IGCObject_DInteger.cpp
@@ -16,9 +16,9 @@
 namespace xo {
     namespace scm {
         auto
-        IGCObject_DInteger::shallow_move(DInteger & self, obj<ACollector> gc) noexcept -> Opaque
+        IGCObject_DInteger::gco_shallow_move(DInteger & self, obj<AGCObjectVisitor> gc) noexcept -> Opaque
         {
-            return self.shallow_move(gc);
+            return self.gco_shallow_move(gc);
         }
         auto
         IGCObject_DInteger::visit_gco_children(DInteger & self, obj<AGCObjectVisitor> fn) noexcept -> void
diff --git a/src/object2/IGCObject_DList.cpp b/src/object2/IGCObject_DList.cpp
index 680d1aa..79ad375 100644
--- a/src/object2/IGCObject_DList.cpp
+++ b/src/object2/IGCObject_DList.cpp
@@ -16,9 +16,9 @@
 namespace xo {
     namespace scm {
         auto
-        IGCObject_DList::shallow_move(DList & self, obj<ACollector> gc) noexcept -> Opaque
+        IGCObject_DList::gco_shallow_move(DList & self, obj<AGCObjectVisitor> gc) noexcept -> Opaque
         {
-            return self.shallow_move(gc);
+            return self.gco_shallow_move(gc);
         }
         auto
         IGCObject_DList::visit_gco_children(DList & self, obj<AGCObjectVisitor> fn) noexcept -> void
diff --git a/src/object2/IGCObject_DRuntimeError.cpp b/src/object2/IGCObject_DRuntimeError.cpp
index 7cce971..800d72b 100644
--- a/src/object2/IGCObject_DRuntimeError.cpp
+++ b/src/object2/IGCObject_DRuntimeError.cpp
@@ -16,9 +16,9 @@
 namespace xo {
     namespace scm {
         auto
-        IGCObject_DRuntimeError::shallow_move(DRuntimeError & self, obj<ACollector> gc) noexcept -> Opaque
+        IGCObject_DRuntimeError::gco_shallow_move(DRuntimeError & self, obj<AGCObjectVisitor> gc) noexcept -> Opaque
         {
-            return self.shallow_move(gc);
+            return self.gco_shallow_move(gc);
         }
         auto
         IGCObject_DRuntimeError::visit_gco_children(DRuntimeError & self, obj<AGCObjectVisitor> fn) noexcept -> void