This returns the Eb/No measured by the demodulator at the far end of the link, relayed back over the EDMAC monitoring channel, with 999 meaning the remote demod is unlocked and 0 meaning EDMAC itself is disabled. Because it reflects the remote receiver's actual signal quality rather than this unit's own, it is the value an admin at the local site checks to know whether the far-end link is healthy without separate access to that remote modem. A reading of 999 while the local Eb/No looks fine would point to a problem specific to the remote site, such as antenna misalignment or an LNB failure, rather than anything on this end.