Index: TODO
===================================================================
diff -u -rbd4aa15282abe386464ef276b78f2708f249f333 -r67591822465e64d9051583c9aa71f8d3a4ef5c96
--- TODO	(.../TODO)	(revision bd4aa15282abe386464ef276b78f2708f249f333)
+++ TODO	(.../TODO)	(revision 67591822465e64d9051583c9aa71f8d3a4ef5c96)
@@ -2880,9 +2880,14 @@
 - new function NsfCallUnkownHandler()
 
 - moved mixin reg type converter to a new file (nsfObj.c)
+- added NsfFilterregObjType, to provide a converter for filter 
+  registration similar to mixin registrations
+- replaced dummy dupIntRepProc and updateStringProc in nsfObj.c by NULL
 
+
 TODO:
 
+- fix memory leak in info-method test
 - in method-require.test
   # TODO: make me more pretty
   set ::nsf::unknown(nx) {::nx::Class __unknown}
Index: generic/nsf.c
===================================================================
diff -u -rbd4aa15282abe386464ef276b78f2708f249f333 -r67591822465e64d9051583c9aa71f8d3a4ef5c96
--- generic/nsf.c	(.../nsf.c)	(revision bd4aa15282abe386464ef276b78f2708f249f333)
+++ generic/nsf.c	(.../nsf.c)	(revision 67591822465e64d9051583c9aa71f8d3a4ef5c96)
@@ -6700,28 +6700,36 @@
  * append a filter command to the 'filterList' of an obj/class
  */
 static int
-FilterAdd(Tcl_Interp *interp, NsfCmdList **filterList, Tcl_Obj *nameObj,
+FilterAdd(Tcl_Interp *interp, NsfCmdList **filterList, Tcl_Obj *filterregObj,
           NsfObject *startingObject, NsfClass *startingClass) {
-  Tcl_Command cmd;
-  int ocName; Tcl_Obj **ovName;
+  Tcl_Obj *filterObj = NULL;
   Tcl_Obj *guardObj = NULL;
+  Tcl_Command cmd;
   NsfCmdList *new;
   NsfClass *cl;
 
-  if (Tcl_ListObjGetElements(interp, nameObj, &ocName, &ovName) == TCL_OK && ocName > 1) {
-    if (ocName == 3 && !strcmp(ObjStr(ovName[1]), NsfGlobalStrings[NSF_GUARD_OPTION])) {
-      nameObj = ovName[0];
-      guardObj = ovName[2];
+  /*
+   * When the provided nameObj is of type NsfFilterregObjType, the nsf specific
+   * converter was called already; otherwise call the converter here.
+   */
+  if (filterregObj->typePtr != &NsfFilterregObjType) {
+    /*fprintf(stderr, "FilterAdd: convert %s in FilterAdd\n", ObjStr(filterregObj));*/
+    if (Tcl_ConvertToType(interp, filterregObj, &NsfFilterregObjType) != TCL_OK) {
+      return TCL_ERROR;
     }
+  } else {
+    /*fprintf(stderr, "FilterAdd: %s already converted\n", ObjStr(filterregObj));*/
   }
 
-  if (!(cmd = FilterSearch(ObjStr(nameObj), startingObject, startingClass, &cl))) {
+  NsfFilterregGet(filterregObj, &filterObj, &guardObj);
+
+  if (!(cmd = FilterSearch(ObjStr(filterObj), startingObject, startingClass, &cl))) {
     if (startingObject) {
       return NsfPrintError(interp, "object filter: can't find filterproc '%s' on %s ",
-			   ObjStr(nameObj), ObjectName(startingObject));
+			   ObjStr(filterObj), ObjectName(startingObject));
     } else {
       return NsfPrintError(interp, "class filter: can't find filterproc '%s' on %s ",
-			   ObjStr(nameObj), ClassName(startingClass));
+			   ObjStr(filterObj), ClassName(startingClass));
     }
   }
 
@@ -9512,6 +9520,37 @@
 
 /*
  *----------------------------------------------------------------------
+ * Nsf_ConvertToFilterreg --
+ *
+ *    Nsf_TypeConverter setting the client data (passed to C functions) to the
+ *    Tcl_Obj. This nsf type converter checks the passed value via the
+ *    NsfFilterregObjType tcl_obj converter, which provides an internal
+ *    representation for the client function.
+ *
+ * Results:
+ *    Tcl result code, *clientData and **outObjPtr
+ *
+ * Side effects:
+ *    None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Nsf_ConvertToFilterreg(Tcl_Interp *interp, Tcl_Obj *objPtr,  Nsf_Param CONST *pPtr,
+	       ClientData *clientData, Tcl_Obj **outObjPtr) {
+  int result;
+  *outObjPtr = objPtr;
+  result = Tcl_ConvertToType(interp, objPtr, &NsfFilterregObjType);
+  if (result == TCL_OK) {
+    *clientData = objPtr;
+    return result;
+  }
+  return NsfObjErrType(interp, NULL, objPtr, "filterreg", (Nsf_Param *)pPtr);
+}
+
+/*
+ *----------------------------------------------------------------------
  * Nsf_ConvertToMixinreg --
  *
  *    Nsf_TypeConverter setting the client data (passed to C functions) to the
@@ -9857,6 +9896,9 @@
   } else if (strncmp(option, "mixinreg", 8) == 0) {
     result = ParamOptionSetConverter(interp, paramPtr, "mixinreg", Nsf_ConvertToMixinreg);
 
+ } else if (strncmp(option, "filterreg", 9) == 0) {
+    result = ParamOptionSetConverter(interp, paramPtr, "filterreg", Nsf_ConvertToFilterreg);
+
   } else if (strncmp(option, "parameter", 9) == 0) {
     result = ParamOptionSetConverter(interp, paramPtr, "parameter", Nsf_ConvertToParameter);
 
Index: generic/nsfInt.h
===================================================================
diff -u -rbd4aa15282abe386464ef276b78f2708f249f333 -r67591822465e64d9051583c9aa71f8d3a4ef5c96
--- generic/nsfInt.h	(.../nsfInt.h)	(revision bd4aa15282abe386464ef276b78f2708f249f333)
+++ generic/nsfInt.h	(.../nsfInt.h)	(revision 67591822465e64d9051583c9aa71f8d3a4ef5c96)
@@ -627,6 +627,9 @@
 extern Tcl_ObjType NsfMixinregObjType;
 int NsfMixinregGet(Tcl_Obj *obj, NsfClass **clPtr, Tcl_Obj **guardObj);
 
+extern Tcl_ObjType NsfFilterregObjType;
+int NsfFilterregGet(Tcl_Obj *obj, Tcl_Obj **filterObj, Tcl_Obj **guardObj);
+
 /* Next Scripting ShadowTclCommands */
 typedef struct NsfShadowTclCommandInfo {
   TclObjCmdProcType proc;
Index: generic/nsfObj.c
===================================================================
diff -u -rbd4aa15282abe386464ef276b78f2708f249f333 -r67591822465e64d9051583c9aa71f8d3a4ef5c96
--- generic/nsfObj.c	(.../nsfObj.c)	(revision bd4aa15282abe386464ef276b78f2708f249f333)
+++ generic/nsfObj.c	(.../nsfObj.c)	(revision 67591822465e64d9051583c9aa71f8d3a4ef5c96)
@@ -14,51 +14,35 @@
 #include "nsfInt.h"
 
 /*
- * Mixinreg type
+ *----------------------------------------------------------------------
  *
- * The mixin reg type is an Tcl_Obj type carrying a class and a guard
- * object. The string representation might have the form "/cls/" or "/cls/
- * -guard /expr/". When no guard expression is provided (first form), the
- * guard entry is NULL.
+ *  Mixinreg Tcl_Obj type --
+ *
+ *      The mixin registration type is an Tcl_Obj type carrying a
+ *      class and a guard object. The string representation might have
+ *      the form "/cls/" or "/cls/ -guard /expr/". When no guard
+ *      expression is provided (first form), the guard entry is NULL.
+ *
+ *----------------------------------------------------------------------
  */
 
 typedef struct {
   NsfClass *mixin;
   Tcl_Obj *guardObj;
 } MixinReg;
 
-static Tcl_DupInternalRepProc	MixinregDupInteralRep;
 static Tcl_FreeInternalRepProc	MixinregFreeInternalRep;
-static Tcl_UpdateStringProc	MixinregUpdateString;
 static Tcl_SetFromAnyProc       MixinregSetFromAny;
 
 Tcl_ObjType NsfMixinregObjType = {
     "nsfMixinreg",			/* name */
     MixinregFreeInternalRep,		/* freeIntRepProc */
-    MixinregDupInteralRep,		/* dupIntRepProc */
-    MixinregUpdateString,		/* updateStringProc */
+    NULL,				/* dupIntRepProc */
+    NULL,				/* updateStringProc */
     MixinregSetFromAny			/* setFromAnyProc */
 };
 
 /* 
- * Dummy placeholder, should never be called.
- */
-static void
-MixinregUpdateString(Tcl_Obj *objPtr) {
-  Tcl_Panic("MixinregUpdateString %s of type %s should not be called", "updateStringProc",
-	    objPtr->typePtr->name);
-}
-
-/* 
- * Dummy placeholder, should never be called.
- */
-static void
-MixinregDupInteralRep(Tcl_Obj *srcPtr, Tcl_Obj *UNUSED(dupPtr)) {
-  Tcl_Panic("MixinregDupInteralRep %s of type %s should not be called", "dupStringProc",
-	    srcPtr->typePtr->name);
-}
-
-/* 
  * freeIntRepProc
  */
 static void
@@ -94,8 +78,8 @@
 {
   NsfClass *mixin = NULL;
   Tcl_Obj *guardObj = NULL, *nameObj;
-  int oc; Tcl_Obj **ov;
   MixinReg *mixinRegPtr;
+  int oc; Tcl_Obj **ov;
 
   if (Tcl_ListObjGetElements(interp, objPtr, &oc, &ov) == TCL_OK) {
     if (oc == 3 && !strcmp(ObjStr(ov[1]), NsfGlobalStrings[NSF_GUARD_OPTION])) {
@@ -174,6 +158,149 @@
 
   return TCL_ERROR;
 }
+
 /*
- * Mixinreg type end
+ *----------------------------------------------------------------------
+ *
+ *  Filterreg Tcl_Obj type --
+ *
+ *      The filter registration type is an Tcl_Obj type carrying a the
+ *      name of a filter and a guard object. The string representation
+ *      might have the form "/filter/" or "/filter/ -guard
+ *      /expr/". When no guard expression is provided (first form),
+ *      the guard entry is NULL. The primary purpose of this converter
+ *      is to provide symmetry to mixinregs and to provide meaningful
+ *      type names for introspection.
+ *
+ *----------------------------------------------------------------------
  */
+
+typedef struct {
+  Tcl_Obj *filterObj;
+  Tcl_Obj *guardObj;
+} Filterreg;
+
+static Tcl_FreeInternalRepProc	FilterregFreeInternalRep;
+static Tcl_SetFromAnyProc       FilterregSetFromAny;
+
+Tcl_ObjType NsfFilterregObjType = {
+    "nsfFilterreg",			/* name */
+    FilterregFreeInternalRep,		/* freeIntRepProc */
+    NULL,				/* dupIntRepProc */
+    NULL,				/* updateStringProc */
+    FilterregSetFromAny			/* setFromAnyProc */
+};
+
+
+/* 
+ * freeIntRepProc
+ */
+static void
+FilterregFreeInternalRep(
+    register Tcl_Obj *objPtr)	/* Filterreg structure object with internal
+				 * representation to free. */
+{
+  Filterreg *filterregPtr = (Filterreg *)objPtr->internalRep.twoPtrValue.ptr1;
+
+  if (filterregPtr != NULL) {
+    /*fprintf(stderr, "FilterregFreeInternalRep freeing filterreg %p class %p guard %p\n",
+      filterregPtr, filterregPtr->class, filterregPtr->guardObj);*/
+    /*
+     * Decrement refCounts
+     */
+    DECR_REF_COUNT(filterregPtr->filterObj);
+    if (filterregPtr->guardObj) {DECR_REF_COUNT(filterregPtr->guardObj);}
+
+    /*
+     * ... and free structure
+     */
+    FREE(Filterreg, filterregPtr);
+  }
+}
+
+/* 
+ * setFromAnyProc
+ */
+static int
+FilterregSetFromAny(
+    Tcl_Interp *interp,		/* Used for error reporting if not NULL. */
+    register Tcl_Obj *objPtr)	/* The object to convert. */
+{
+  Tcl_Obj *guardObj = NULL, *filterObj;
+  Filterreg *filterregPtr;
+  int oc; Tcl_Obj **ov;
+
+  if (Tcl_ListObjGetElements(interp, objPtr, &oc, &ov) == TCL_OK) {
+    if (oc == 3 && !strcmp(ObjStr(ov[1]), NsfGlobalStrings[NSF_GUARD_OPTION])) {
+      filterObj = ov[0];
+      guardObj = ov[2];
+      /*fprintf(stderr, "mixinadd name = '%s', guard = '%s'\n", ObjStr(name), ObjStr(guard));*/
+    } else if (oc == 1) {
+      filterObj = ov[0];
+    } else {
+      return TCL_ERROR;
+    }
+  } else {
+    return TCL_ERROR;
+  }
+
+  /*
+   * Conversion was ok.
+   * Allocate structure ... 
+   */
+  filterregPtr = NEW(Filterreg);
+
+  /*
+   * ... and increment refCounts
+   */
+  INCR_REF_COUNT(filterObj);
+  if (guardObj) {INCR_REF_COUNT(guardObj);}
+
+  filterregPtr->filterObj = filterObj;
+  filterregPtr->guardObj = guardObj;
+
+  /*fprintf(stderr, "FilterregSetFromAny alloc filterreg %p class %p guard %p\n",
+    filterregPtr, filterregPtr->mixin, filterregPtr->guardObj);*/
+
+  /*
+   * Free the old interal representation and store own structure as internal
+   * representation.
+   */
+  TclFreeIntRep(objPtr);
+  objPtr->internalRep.twoPtrValue.ptr1 = (void *)filterregPtr;
+  objPtr->internalRep.twoPtrValue.ptr2 = NULL;
+  objPtr->typePtr = &NsfFilterregObjType;
+
+  return TCL_OK;
+}
+/*
+ *----------------------------------------------------------------------
+ *
+ * NsfFilterregGet --
+ *
+ *      Return the internal representation of a filterreg obj type to
+ *      keep internal rep local to this file.
+ *
+ * Results:
+ *      Tcl result code, arg two and three on success.
+ *
+ * Side effects:
+ *      None
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+NsfFilterregGet(Tcl_Obj *obj, Tcl_Obj **filterObj, Tcl_Obj **guardObj) {
+  if (obj->typePtr == &NsfFilterregObjType) {
+    Filterreg *filterregPtr = obj->internalRep.twoPtrValue.ptr1;
+    *filterObj = filterregPtr->filterObj;
+    *guardObj = filterregPtr->guardObj;
+    return TCL_OK;
+  }
+
+  return TCL_ERROR;
+}
+/*
+ * Filterreg type end
+ */
Index: library/nx/nx.tcl
===================================================================
diff -u -r756a5ed4e51921ada898fdf69cc7bd2c5c616828 -r67591822465e64d9051583c9aa71f8d3a4ef5c96
--- library/nx/nx.tcl	(.../nx.tcl)	(revision 756a5ed4e51921ada898fdf69cc7bd2c5c616828)
+++ library/nx/nx.tcl	(.../nx.tcl)	(revision 67591822465e64d9051583c9aa71f8d3a4ef5c96)
@@ -1020,7 +1020,7 @@
     # Obtain a list of parameter options from slot object
     #
     set options [list]
-    if {[info exists :elementtype] && ${:elementtype} ni {{} mixin}} {
+    if {[info exists :elementtype] && ${:elementtype} ne {}} {
       lappend options ${:elementtype}
       #puts stderr "+++ [self] added elementtype ${:elementtype}"
     }
@@ -1138,7 +1138,7 @@
       #
       # Value contains globbing meta characters.
       #
-      if {[info exists :elementtype] && ${:elementtype} ne "" 
+      if {[info exists :elementtype] && ${:elementtype} eq "mixinreg" 
 	  && ![string match ::* $value]} {
 	#
         # Prefix glob pattern with ::, since all object names have
@@ -1147,10 +1147,10 @@
         set value ::$value
       }
       return [lsearch -all -not -glob -inline $old $value]
-    } elseif {[info exists :elementtype] && ${:elementtype} ne ""} {
+    } elseif {[info exists :elementtype] && ${:elementtype} eq "mixinreg"} {
       #
-      # Value contains no globbing meta characters, but elementtype is
-      # given.
+      # Value contains no globbing meta characters, and elementtype could be
+      # fully qualified
       #
       if {[string first :: $value] == -1} {
 	#
@@ -1216,12 +1216,12 @@
     ::nx::RelationSlot create ${os}::Object::slot::mixin \
 	-forwardername object-mixin -elementtype mixinreg
     ::nx::RelationSlot create ${os}::Object::slot::filter \
-	-forwardername object-filter
+	-forwardername object-filter -elementtype filterreg
 
     ::nx::RelationSlot create ${os}::Class::slot::mixin \
 	-forwardername class-mixin -elementtype mixinreg
     ::nx::RelationSlot create ${os}::Class::slot::filter \
-        -forwardername class-filter
+        -forwardername class-filter -elementtype filterreg
 
     #
     # Create two convenience object parameters to allow configuration
@@ -1230,7 +1230,7 @@
     ::nx::ObjectParameterSlot create ${os}::Class::slot::object-mixin \
 	-methodname "::nsf::classes::nx::Object::mixin" -elementtype mixinreg
     ::nx::ObjectParameterSlot create ${os}::Class::slot::object-filter \
-	-methodname "::nsf::classes::nx::Object::filter"
+	-methodname "::nsf::classes::nx::Object::filter" -elementtype filterreg
 
     #
     # Create object parameter slots for "attributes", "noninit" and "volatile"
Index: tests/info-method.test
===================================================================
diff -u -r03990ee9d7185ded72b0fa05e81f848e866451c2 -r67591822465e64d9051583c9aa71f8d3a4ef5c96
--- tests/info-method.test	(.../info-method.test)	(revision 03990ee9d7185ded72b0fa05e81f848e866451c2)
+++ tests/info-method.test	(.../info-method.test)	(revision 67591822465e64d9051583c9aa71f8d3a4ef5c96)
@@ -493,10 +493,10 @@
     :method "sub foo" args {;}
   }
 
-  ? {C info parameter syntax} "?-a value? ?-b value? ?-volatile? ?-noinit? ?-mixin mixinreg ...? ?-class class? ?-filter value ...? ?__initcmd?"
+  ? {C info parameter syntax} "?-a value? ?-b value? ?-volatile? ?-noinit? ?-mixin mixinreg ...? ?-class class? ?-filter filterreg ...? ?__initcmd?"
   ? {C info parameter syntax a} "?-a value?"
 
-  ? {C info parameter spec} "-a {-b 1} -volatile:alias,noarg -noinit:alias,method=::nsf::methods::object::noinit,noarg -mixin:mixinreg,alias,1..n -class:class,alias,method=::nsf::methods::object::class -filter:alias,1..n __initcmd:initcmd,optional"
+  ? {C info parameter spec} "-a {-b 1} -volatile:alias,noarg -noinit:alias,method=::nsf::methods::object::noinit,noarg -mixin:mixinreg,alias,1..n -class:class,alias,method=::nsf::methods::object::class -filter:filterreg,alias,1..n __initcmd:initcmd,optional"
 
   ? {C info parameter list} "-a -b -volatile -noinit -mixin -class -filter __initcmd"
   ? {C info parameter name} "a b volatile noinit mixin class filter __initcmd"
Index: tests/interceptor-slot.test
===================================================================
diff -u -rb3018d3be0f1524a3f1709edc0e2ddb5d8bc4c0b -r67591822465e64d9051583c9aa71f8d3a4ef5c96
--- tests/interceptor-slot.test	(.../interceptor-slot.test)	(revision b3018d3be0f1524a3f1709edc0e2ddb5d8bc4c0b)
+++ tests/interceptor-slot.test	(.../interceptor-slot.test)	(revision 67591822465e64d9051583c9aa71f8d3a4ef5c96)
@@ -9,109 +9,121 @@
 }
 Class create M2
 Class create C 
-
-? {C info lookup method mixin} "::nsf::classes::nx::Class::mixin"
-C mixin M
-? {C info precedence} "::nx::Class ::nx::Object"
-? {C mixin} "::M"
-? {C info mixin classes} "::M"
 C create c1
-? {c1 info precedence} "::M ::C ::nx::Object"
-C mixin add M2
-? {c1 info precedence} "::M2 ::M ::C ::nx::Object"
-C mixin delete M2
-? {c1 info precedence} "::M ::C ::nx::Object"
-C mixin delete M
-? {C info mixin classes} ""
-C mixin ::M
-C mixin {}
-? {C info mixin classes} ""
 
 #
+# test mixin method
+#
+Test case mixin-method {
+  ? {C info lookup method mixin} "::nsf::classes::nx::Class::mixin"
+  ? {C mixin M} ::M
+  ? {C info precedence} "::nx::Class ::nx::Object"
+  ? {C mixin} "::M"
+  ? {C info mixin classes} "::M"
+  ? {c1 info precedence} "::M ::C ::nx::Object"
+  ? {C mixin add M2} "::M2 ::M"
+  ? {c1 info precedence} "::M2 ::M ::C ::nx::Object"
+  ? {C mixin delete M2} "::M"
+  ? {c1 info precedence} "::M ::C ::nx::Object"
+  ? {C mixin delete M} ""
+  ? {C info mixin classes} ""
+  ? {C mixin ::M} "::M"
+  ? {C mixin {}} ""
+  ? {C info mixin classes} ""
+}
+
+#
 # test nsf::mixin interface
 #
-::nsf::mixin C ::M
-? {C info mixin classes} "::M"
-::nsf::mixin C ::M2
-? {C info mixin classes} "::M2 ::M"
-::nsf::mixin C ""
-? {C info mixin classes} ""
+Test case nsf-mixin {
+  ? {::nsf::mixin C ::M} "::M"
+  ? {C info mixin classes} "::M"
+  ? {::nsf::mixin C ::M2} "::M2 ::M"
+  ? {C info mixin classes} "::M2 ::M"
+  ? {::nsf::mixin C ""} ""
+  ? {C info mixin classes} ""
+}
 
+#
 # per-object mixins
-? {c1 info precedence} "::C ::nx::Object"
-c1 mixin add M
-? {::nsf::relation c1 object-mixin} ::M
-? {catch {c1 mixin UNKNOWN}} 1
-? {::nsf::relation c1 object-mixin} "::M"
+#
+Test case per-object-mixin {
+  ? {c1 info precedence} "::C ::nx::Object"
+  ? {c1 mixin add M} ::M
+  ? {::nsf::relation c1 object-mixin} ::M
+  ? {catch {c1 mixin UNKNOWN}} 1
+  ? {::nsf::relation c1 object-mixin} "::M"
 
-# add again the same mixin
-c1 mixin add M
-? {c1 info precedence} "::M ::C ::nx::Object"
-c1 mixin add M2
-? {c1 info precedence} "::M2 ::M ::C ::nx::Object"
-c1 mixin delete M
-? {c1 info precedence} "::M2 ::C ::nx::Object"
-c1 mixin delete M2
-? {c1 info precedence} "::C ::nx::Object"
+  # add again the same mixin
+  ? {c1 mixin add M} {::M}
+  ? {c1 info precedence} "::M ::C ::nx::Object"
+  ? {c1 mixin add M2} "::M2 ::M"
+  ? {c1 info precedence} "::M2 ::M ::C ::nx::Object"
+  ? {c1 mixin delete M} "::M2"
+  ? {c1 info precedence} "::M2 ::C ::nx::Object"
+  ? {c1 mixin delete M2} ""
+  ? {c1 info precedence} "::C ::nx::Object"
+}
 
 #
 # adding, removing per-object mixins for classes through relation
 # "object-mixin"
 #
-::nsf::relation C object-mixin M
-? {C info precedence} "::M ::nx::Class ::nx::Object"
-? {C class info mixin classes} "::M"
-::nsf::relation C object-mixin ""
-? {C info precedence} "::nx::Class ::nx::Object"
+Test case object-mixin-relation {
+  ? {::nsf::relation C object-mixin M} ::M
+  ? {C info precedence} "::M ::nx::Class ::nx::Object"
+  ? {C class info mixin classes} "::M"
+  ? {::nsf::relation C object-mixin ""} ""
+  ? {C info precedence} "::nx::Class ::nx::Object"
+}
 
 #
 # adding, removing per-object mixins for classes through slot
 # "object-mixin"
 #
-# C object-mixin M
-# ? {C info precedence} "::M ::nx::Class ::nx::Object"
-# ? {C class info mixin classes} "::M"
-# C object-mixin ""
-# ? {C info precedence} "::nx::Class ::nx::Object"
+ # C object-mixin M
+ # ? {C info precedence} "::M ::nx::Class ::nx::Object"
+ # ? {C class info mixin classes} "::M"
+ # C object-mixin ""
+ # ? {C info precedence} "::nx::Class ::nx::Object"
 
 #
-# add and remove class mixin for classes via modifier "object" and
+# add and remove class mixin for classes via modifier "class" and
 # "mixin"
 #
-C class mixin M
-? {C info precedence} "::M ::nx::Class ::nx::Object"
-? {C class info mixin classes} "::M"
-C class mixin ""
-? {C info precedence} "::nx::Class ::nx::Object"
+Test case class+mixin {
+  ? {C class mixin M} ::M
+  ? {C info precedence} "::M ::nx::Class ::nx::Object"
+  ? {C class info mixin classes} "::M"
+  ? {C class mixin ""} ""
+  ? {C info precedence} "::nx::Class ::nx::Object"
+}
 
 #
 #  add and remove class mixin for classes via class mixin add
 #
-C class mixin add M
-? {C info precedence} "::M ::nx::Class ::nx::Object"
-? {C class info mixin classes} "::M"
-C class mixin ""
-? {C info precedence} "::nx::Class ::nx::Object"
+Test case class+mixin-add {
+  ? {C class mixin add M} ::M
+  ? {C info precedence} "::M ::nx::Class ::nx::Object"
+  ? {C class info mixin classes} "::M"
+  ? {C class mixin ""} ""
+  ? {C info precedence} "::nx::Class ::nx::Object"
+  
+  ? {C class mixin add M} ::M
+  ? {C info precedence} "::M ::nx::Class ::nx::Object"
+  ? {::nsf::relation C object-mixin} ::M
+  ? {catch {C class mixin add UNKNOWN}} 1
+  ? {::nsf::relation C object-mixin} "::M"
+  ? {C class mixin ""} ""
+  ? {C info precedence} "::nx::Class ::nx::Object"
 
-#
-# adding per-object mixins for classes via "object mixin add M"
-#
-C class mixin add M 
-? {C info precedence} "::M ::nx::Class ::nx::Object"
-? {::nsf::relation C object-mixin} ::M
-? {catch {C class mixin add UNKNOWN}} 1
-? {::nsf::relation C object-mixin} "::M"
-C class mixin ""
-? {C info precedence} "::nx::Class ::nx::Object"
+  ? {C class mixin M} ::M
+  ? {C info precedence} "::M ::nx::Class ::nx::Object"
 
-#
-# adding per-object mixins for classes via "object mixin M"
-#
-C class mixin M 
-? {C info precedence} "::M ::nx::Class ::nx::Object"
+  # forwarder with 0 arguments + flag
+  ? {C class mixin} "::M"
+}
 
-# forwarder with 0 arguments + flag
-? {C class mixin} "::M"
 
 
 Test case mixin-add {
Index: tests/parameters.test
===================================================================
diff -u -r03990ee9d7185ded72b0fa05e81f848e866451c2 -r67591822465e64d9051583c9aa71f8d3a4ef5c96
--- tests/parameters.test	(.../parameters.test)	(revision 03990ee9d7185ded72b0fa05e81f848e866451c2)
+++ tests/parameters.test	(.../parameters.test)	(revision 67591822465e64d9051583c9aa71f8d3a4ef5c96)
@@ -249,7 +249,7 @@
   C create c1
  
   ? {C eval :objectparameter} \
-      "-a -b:boolean {-c 1} -volatile:alias,noarg -noinit:alias,method=::nsf::methods::object::noinit,noarg -mixin:mixinreg,alias,1..n -class:class,alias,method=::nsf::methods::object::class -filter:alias,1..n __initcmd:initcmd,optional"
+      "-a -b:boolean {-c 1} -volatile:alias,noarg -noinit:alias,method=::nsf::methods::object::noinit,noarg -mixin:mixinreg,alias,1..n -class:class,alias,method=::nsf::methods::object::class -filter:filterreg,alias,1..n __initcmd:initcmd,optional"
 
   ? {c1 eval :objectparameter} \
       "::c1: unable to dispatch method 'objectparameter'"
@@ -276,7 +276,7 @@
       "::D::slot::d ::C::slot::a ::C::slot::b ::C::slot::c"
   
   ? {D eval :objectparameter} \
-      "-d:required -a -b:boolean {-c 1} -volatile:alias,noarg -noinit:alias,method=::nsf::methods::object::noinit,noarg -mixin:mixinreg,alias,1..n -class:class,alias,method=::nsf::methods::object::class -filter:alias,1..n __initcmd:initcmd,optional"
+      "-d:required -a -b:boolean {-c 1} -volatile:alias,noarg -noinit:alias,method=::nsf::methods::object::noinit,noarg -mixin:mixinreg,alias,1..n -class:class,alias,method=::nsf::methods::object::class -filter:filterreg,alias,1..n __initcmd:initcmd,optional"
 }
 
 #######################################################
@@ -293,29 +293,29 @@
   D mixin M
 
   ? {D eval :objectparameter} \
-      "-b -m1 -m2 -d:required -a {-c 1} -volatile:alias,noarg -noinit:alias,method=::nsf::methods::object::noinit,noarg -mixin:mixinreg,alias,1..n -class:class,alias,method=::nsf::methods::object::class -filter:alias,1..n __initcmd:initcmd,optional" \
+      "-b -m1 -m2 -d:required -a {-c 1} -volatile:alias,noarg -noinit:alias,method=::nsf::methods::object::noinit,noarg -mixin:mixinreg,alias,1..n -class:class,alias,method=::nsf::methods::object::class -filter:filterreg,alias,1..n __initcmd:initcmd,optional" \
     "mixin added"
 
   M mixin M2
 
   ? {D eval :objectparameter} \
-      "-b2 -b -m1 -m2 -d:required -a {-c 1} -volatile:alias,noarg -noinit:alias,method=::nsf::methods::object::noinit,noarg -mixin:mixinreg,alias,1..n -class:class,alias,method=::nsf::methods::object::class -filter:alias,1..n __initcmd:initcmd,optional" \
+      "-b2 -b -m1 -m2 -d:required -a {-c 1} -volatile:alias,noarg -noinit:alias,method=::nsf::methods::object::noinit,noarg -mixin:mixinreg,alias,1..n -class:class,alias,method=::nsf::methods::object::class -filter:filterreg,alias,1..n __initcmd:initcmd,optional" \
     "transitive mixin added"
   D mixin ""
   #we should have again the old interface
 
   ? {D eval :objectparameter} \
-      "-d:required -a -b:boolean {-c 1} -volatile:alias,noarg -noinit:alias,method=::nsf::methods::object::noinit,noarg -mixin:mixinreg,alias,1..n -class:class,alias,method=::nsf::methods::object::class -filter:alias,1..n __initcmd:initcmd,optional"
+      "-d:required -a -b:boolean {-c 1} -volatile:alias,noarg -noinit:alias,method=::nsf::methods::object::noinit,noarg -mixin:mixinreg,alias,1..n -class:class,alias,method=::nsf::methods::object::class -filter:filterreg,alias,1..n __initcmd:initcmd,optional"
 
   C mixin M
   ? {D eval :objectparameter} \
-      "-b2 -b -m1 -m2 -d:required -a {-c 1} -volatile:alias,noarg -noinit:alias,method=::nsf::methods::object::noinit,noarg -mixin:mixinreg,alias,1..n -class:class,alias,method=::nsf::methods::object::class -filter:alias,1..n __initcmd:initcmd,optional" \
+      "-b2 -b -m1 -m2 -d:required -a {-c 1} -volatile:alias,noarg -noinit:alias,method=::nsf::methods::object::noinit,noarg -mixin:mixinreg,alias,1..n -class:class,alias,method=::nsf::methods::object::class -filter:filterreg,alias,1..n __initcmd:initcmd,optional" \
     "mixin added"
   C mixin ""
   #we should have again the old interface
   
   ? {D eval :objectparameter} \
-      "-d:required -a -b:boolean {-c 1} -volatile:alias,noarg -noinit:alias,method=::nsf::methods::object::noinit,noarg -mixin:mixinreg,alias,1..n -class:class,alias,method=::nsf::methods::object::class -filter:alias,1..n __initcmd:initcmd,optional" 
+      "-d:required -a -b:boolean {-c 1} -volatile:alias,noarg -noinit:alias,method=::nsf::methods::object::noinit,noarg -mixin:mixinreg,alias,1..n -class:class,alias,method=::nsf::methods::object::class -filter:filterreg,alias,1..n __initcmd:initcmd,optional" 
 }
 
 #######################################################
@@ -1617,7 +1617,7 @@
 
   ? {C info slots -closure} "::C::slot::a1 ::nx::Object::slot::volatile ::nx::Object::slot::noinit ::nx::Object::slot::mixin ::nx::Object::slot::__initcmd ::nx::Object::slot::class ::nx::Object::slot::filter"
 
-  ? {C eval :objectparameter} "-a1 -volatile:alias,noarg -noinit:alias,method=::nsf::methods::object::noinit,noarg -mixin:mixinreg,alias,1..n -class:class,alias,method=::nsf::methods::object::class -filter:alias,1..n __initcmd:initcmd,optional"
+  ? {C eval :objectparameter} "-a1 -volatile:alias,noarg -noinit:alias,method=::nsf::methods::object::noinit,noarg -mixin:mixinreg,alias,1..n -class:class,alias,method=::nsf::methods::object::class -filter:filterreg,alias,1..n __initcmd:initcmd,optional"
 
   #
   # invalidate object parameter and expect that the per-class mixin
@@ -1631,7 +1631,7 @@
 
   ? {C info slots -closure} "::C::slot::a1 ::nx::Object::slot::volatile ::nx::Object::slot::noinit ::nx::Object::slot::mixin ::nx::Object::slot::__initcmd ::nx::Object::slot::class ::nx::Object::slot::filter"
 
-  ? {C eval :objectparameter} "-a1 -volatile:alias,noarg -noinit:alias,method=::nsf::methods::object::noinit,noarg -mixin:mixinreg,alias,1..n -class:class,alias,method=::nsf::methods::object::class -filter:alias,1..n __initcmd:initcmd,optional"
+  ? {C eval :objectparameter} "-a1 -volatile:alias,noarg -noinit:alias,method=::nsf::methods::object::noinit,noarg -mixin:mixinreg,alias,1..n -class:class,alias,method=::nsf::methods::object::class -filter:filterreg,alias,1..n __initcmd:initcmd,optional"
 
   # should not require b1
   ? {C create c2} ::c2