This FM check if an "activity" is allowed for an "object" in its current status.
e.g. : Can we allocate some activity on a service order, can we complete a service notification, etc.
Look at customizing transaction BS02 until BS53 transaction, those maintain the link between object, operations and status (which status are pertinent on which object, which status allow which operation, which status is positioned by which operation, etc)
Regards
