one of the documented procedures in this installation of the ACS
ug_return_error   title   explanation   db   group_id   group_name   admin_email
What it does:
this function should be used if we want to indicate an error to the user, which was produced by bug in our code. it returns error message properly formatted for user_groups.
Defined in: /web/philip/tcl/user-group-defs.tcl

Source code:

    ns_return 500 text/html "
    [ug_header $title $db $group_id]
    [ug_page_title $title $db $group_id $group_name]
    [ug_footer $admin_email]"