Loopback status of each cable from the port to the star coupler.
The field applies only to CI. Possible displays are:
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.