The value identifies the current PU state. This has
a different meaning for direct or DLUR PU before the
link station is established.
For DLUR PU, the PU is in reset state, for direct PU,
this will be either sending a TEST or XID
shut (1) - The PU is configured but in shut state
reset (2) - The link station of this PU is not active.
inactive (3) - The PU is not activated and the link-station
or DLUR state is unknown.
test (4) - PU is sending a TEST to establish link.
xid (5) - TEST is responded, XID is sent.
pActpu (6) - The link station is up but no ACTPU is
received.
active (7) - ACTPU is received and acknowledged positively.
actBusy (8) - Awaiting host to acknowledge the SSCP-PU data.