This attribute is the most recent A-Bit status received from the
interface. It is an indication from the equipment attached to the
interface on whether it is ready to accept data. Mpanl relays the A-
Bit status from interface to the other end of the SPVC. When an
inactive setting is received, Mpanl will discard any data offered
from the subnet. When an active setting is received, Mpanl will try
to relay all data offered from the subnet to the interface.