tt...tt nn...nn mm...mm xx...xx

tt...tt: Request message type

SYNC: Synchronous

IO: Asynchronous inquiry-response

NORM: Asynchronous normal branch

PRIO: Asynchronous priority branch

nn....nn: Number of unsent messages

mm....mm: First serial number of unsent messages

xx....xx: Last serial number of unsent messages

If the serial numbers wrap, the first serial number may be greater than the last serial number.

S: Displays the status of the send queue.