Index: openacs-4/packages/acs-templating/tcl/data-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-templating/tcl/data-procs.tcl,v
diff -u -r1.23.2.10 -r1.23.2.11
--- openacs-4/packages/acs-templating/tcl/data-procs.tcl	30 Jun 2021 08:26:18 -0000	1.23.2.10
+++ openacs-4/packages/acs-templating/tcl/data-procs.tcl	1 Jul 2021 13:54:56 -0000	1.23.2.11
@@ -276,8 +276,7 @@
 
     upvar 2 $message_ref message $value_ref value
 
-    set expr {^(https?://)?([a-zA-Z0-9_\-\.]+(:[0-9]+)?)?[a-zA-Z0-9_.%/?=&-]+$}
-    set result [regexp $expr $value]
+    set result [util_url_valid_p -relative $value]
 
     if { ! $result } {
         set message "[_ acs-templating.Invalid_url] \"[ns_quotehtml $value]\""