one of the documented procedures in this installation of the ACS
ug_return_complaint   exception_count   exception_text   db   group_id   group_name   admin_email
What it does:
Return a page complaining about the user's input (as opposed to an error in our software, for which ug_return_error is more appropriate). This pages are changed in order to use ug_header and ug_footer
Defined in: /web/philip/tcl/user-group-defs.tcl

Source code:

    # there was an error in the user input 
    if { $exception_count == 1 } {
	set problem_string "a problem"
	set please_correct "it"
    } else {
	set problem_string "some problems"
	set please_correct "them"
    ns_return 200 text/html "
    [ug_header "Problem with Your Input" $db $group_id]
    [ug_page_title "Problem with Your Input" $db $group_id $group_name]

    We had $problem_string processing your entry:
    Please back up using your browser, correct $please_correct, and
    resubmit your entry.
    Thank you.
    [ug_footer $admin_email]