one of the documented procedures in this installation of the ACS
im_spam_number_users   db   group_id_list   { all_or_any "all" }
What it does:
Returns the number of users that belong to all/any of the groups in the comma separated list of group ids (group_id_list)
Defined in: /web/philip/tcl/intranet-defs.tcl

Source code:

    if { "$all_or_any" == "all" } {
	set ugm_clause [im_spam_multi_group_exists_clause $group_id_list]
    } else {
	set ugm_clause "and ugm.group_id in ($group_id_list)"
    return [database_to_tcl_string $db  "select count(distinct u.user_id)
               from users_active u, user_group_map ugm
              where u.user_id=ugm.user_id $ugm_clause"]