Loopback status of each cable from the port to the star coupler.
The field applies only to CI. Possible displays are as follows:
A-B - Loopback tests pass on paths A and B.
A-# - Loopback tests pass on path A.
#-B - Loopback tests pass on path B.
#-# - Loopback tests failed on paths A and B.
N/A - Loopback tests are not being done.