This attribute is the most recent A-Bit status sent to the interface.
The A-Bit status is originated from the SPVC end point at the
remote end of the Passport subnet and it is relayed to the interface
by Mpanl. When an inactive setting is sent out, Mpanl will discard
any data offered from the interface. When an active setting is sent
out, Mpanl will try to relay all data offered from the interface to the
other end of the SPVC.