Index: generic/xotclError.c
===================================================================
diff -u -rc6066a15de738754028991b2b57b8f1d5a1cccaa -rc942f4e117d2aa3c8594702e0476a3f73a4147df
--- generic/xotclError.c	(.../xotclError.c)	(revision c6066a15de738754028991b2b57b8f1d5a1cccaa)
+++ generic/xotclError.c	(.../xotclError.c)	(revision c942f4e117d2aa3c8594702e0476a3f73a4147df)
@@ -108,9 +108,11 @@
 }
 
 extern int
-XOTclObjErrType(Tcl_Interp *interp, Tcl_Obj *value, char *type) {
+XOTclObjErrType(Tcl_Interp *interp, Tcl_Obj *value, char *type, char *parameterName) {
   Tcl_ResetResult(interp);
   Tcl_AppendResult(interp,"expected ", type, " but got \"",  ObjStr(value), "\"", 
+                   parameterName ? " for parameter " : "",
+                   parameterName ? parameterName : "",
                    (char *) NULL);
   return TCL_ERROR;
 }