Index: openacs-4/packages/categories/www/cadmin/category-form.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/categories/www/cadmin/category-form.tcl,v
diff -u -N -r1.14 -r1.15
--- openacs-4/packages/categories/www/cadmin/category-form.tcl	29 Jun 2018 17:27:18 -0000	1.14
+++ openacs-4/packages/categories/www/cadmin/category-form.tcl	12 Feb 2019 17:12:19 -0000	1.15
@@ -6,7 +6,7 @@
 } {
     tree_id:naturalnum,notnull
     category_id:naturalnum,optional
-    {parent_id:naturalnum,optional [db_null]}
+    {parent_id:naturalnum,optional ""}
     {locale ""}
     object_id:naturalnum,optional
     ctx_id:naturalnum,optional