Index: openacs-4/packages/categories/tcl/categories-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/categories/tcl/categories-procs.tcl,v
diff -u -N -r1.38 -r1.38.2.1
--- openacs-4/packages/categories/tcl/categories-procs.tcl	18 Sep 2018 18:28:55 -0000	1.38
+++ openacs-4/packages/categories/tcl/categories-procs.tcl	14 Feb 2019 16:15:01 -0000	1.38.2.1
@@ -160,7 +160,7 @@
 ad_proc -public category::change_parent {
     -category_id:required
     -tree_id:required
-    {-parent_id [db_null]}
+    {-parent_id ""}
 } {
     Changes parent category of a category.
     @option category_id category_id whose parent should change.
@@ -374,7 +374,7 @@
     Gets the category name in the specified language, if available.
     Use default language otherwise.
 
-    @param category_ids  category_ids for which to get the name. 
+    @param category_ids  category_ids for which to get the name.
     @param locale       language in which to get the name. [ad_conn locale] used by default.
     @return list of names corresponding to the list of category_id's supplied.
     @author Timo Hentschel (timo@timohentschel.de)