Indicates the current state of the channel.
Bit 0 - Signal Degrade (SD) Condition. Indicates a 'soft
failure' condition resulting from the Line BER exceeding a
pre-selected threshold.
Bit 1 - Signal Fail (SF) Condition. Indicates a 'hard failure'
condition detected on the incoming OC-N signal.
Bit 2 - Locked Out. This bit, when applied to a working
channel, indicates that the channel is prevented from switching
to the protection line. When applied to the null channel, this
bit indicates that no working channel may switch to the
protection line.
The remaining states only apply to working channels which have
attempted to initiate an automatic protection switch.
Bit 3 - Switched. Indictes that the working channel is
currently switched to the protection line.
Bit 4 - Both Lines Failed. Indictes that both the working line
and the protection line are currently in a failure state.
Bit 5 - Protection Line Busy. Indictes that the protection line
is busy servicing a different working channel. (This condition
can only occur in the 1:n architecture.)