one of the documented procedures in this installation of the ACS
ad_scope_return_error   title   explanation   db
What it does:
if scope is not set in the topmost environment then public scope is assumed. if scope=group, it assumes that group_vars_set is set in the topmost environment. 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 appropriate scope.
Defined in: /web/philip/tcl/ad-scope.tcl

Source code:

    if { [uplevel [ad_scope_upvar_level] {info exists scope}] } {
	upvar [ad_scope_upvar_level] scope scope
    } else {
	set scope public

    switch $scope {
	public {
	    return [ad_return_error $title $explanation]
	group {
	    upvar [ad_scope_upvar_level] group_vars_set group_vars_set
	    set group_id [ns_set get $group_vars_set group_id]
	    set group_name [ns_set get $group_vars_set group_name]
	    set group_admin_email [ns_set get $group_vars_set group_admin_email]
	    return [ug_return_error $title $explanation $db $group_id $group_name $group_admin_email]
	user {
	    # this may be later modified if we allow users to customize the display of their pages
	    return [ad_return_error $title $explanation]