one of the documented procedures in this installation of the ACS
bboard_validate_msg_id {} msg_id
What it does:
Validates that this is a legitimate message ID. Throws an error if invalid, returns msg_id if valid.
Defined in: /web/philip/tcl/bboard-defs.tcl

Source code:

arg_parser_for_bboard_validate_msg_id $args

    if { ![regexp {^[0-9a-zA-Z]+$} $msg_id]} {
	error "Invalid msg_id specified"
    } elseif {[string length $msg_id] > 6} {
	error "Message ID too long"
    return $msg_id