Knowing how old a specific transceiver is helps the admin judge whether age-related degradation, like the laser-bias creep described for cienaCesPortXcvrBias, is a plausible explanation for symptoms on this particular optic, versus a young unit where a different root cause should be suspected first. For example, a manufacture date of 2015-03 on an optic showing high bias current today would support an aging-laser diagnosis, while the same symptom on an optic dated last month would not.