It's the difference between sending/receiving valid data. Maxim has a more detailed laymen explanation https://www.maximintegrated.com/en/design/technical-documents/app-notes/1/174.html
If you don't have shell access you can read the calibration data from eeprom A2h as described in the datasheet of the SPS-34-24T-HP-TDFO https://www.sourcephotonics.com/wp-content/uploads/2017/08/DS-8085-02_SPS-34-24T-HP-TDFO.pdf which is the OEM of the Alcatel-Lucent G-010S-P and its later copy Huawei MA5671A.
ethtool -m on Linux and I'm uncertain if BSD goes beyond A0h but ifconfig -vvv where addtitional v's increase the verbosity level.
Calibration is performed by /opt/lantiq/bin/ocal but as I said before I have never looked into it. If you have shell access and run uci show goi_config you'll see all the calibration data.