one of the documented procedures in this installation of the ACS
im_group_id_from_parameter   parameter   { db "" }
What it does:
Returns the group_id for the group with the GroupShortName specified in the server .ini file for $parameter. That is, we look up the specified parameter in the intranet module of the parameters file, and use that short_name to find a group id. Memoizes the result
Defined in: /web/philip/tcl/intranet-defs.tcl

Source code:

    set short_name [ad_parameter $parameter intranet]
    if { [empty_string_p $short_name] } {
	uplevel {
	    ad_return_error "Missing parameter" "Parameter not defined in the intranet section of your server's parameters file"

    return [util_memoize "im_group_id_from_parameter_helper $short_name $db"]