Index: library/nx/nx.tcl
===================================================================
diff -u -rbabe6447be02524ff70f5af3ee83ae5aa678b6d1 -red365a90fa455e82a281fc1b4bfaa4b96081da12
--- library/nx/nx.tcl	(.../nx.tcl)	(revision babe6447be02524ff70f5af3ee83ae5aa678b6d1)
+++ library/nx/nx.tcl	(.../nx.tcl)	(revision ed365a90fa455e82a281fc1b4bfaa4b96081da12)
@@ -2482,18 +2482,21 @@
     }
 
     lassign [::nx::MetaSlot parseParameterSpec -class $class -target [self] $spec] \
-               pname parameterOptions _ _
+               pname parameterOptions _ options
 
-    set paramOptsList [split $parameterOptions ,]
     if {[info exists defaultValue]
-        && ("substdefault" in $paramOptsList || [lsearch $paramOptsList "substdefault=*"])} {
+        && [dict exists $options -substdefault]
+      } {
       if {[string match {*\[*\]*} $defaultValue]} {
         if {![info complete $defaultValue]} {
           return -code error "substdefault: default '$defaultValue' is not a complete script"
         }
       } else {
-        set paramOptsList [lsearch -exact -inline -all -not $paramOptsList "substdefault"]
-        set spec [string trimright $pname:[join $paramOptsList ,] :]
+        #
+        # Rewrite the spec such is has no "substdefault" value
+        #
+        #set paramOptsList1 [lsearch -glob -inline -all -not [split $parameterOptions ,] "substdefault*"]
+        #set spec [string trimright $pname:[join $paramOptsList1 ,] :]
       }
     }