xpdrFecMode selects the Forward Error Correction behavior applied to 10G and 16G services on this transponder connection, choosing between no FEC, FEC monitoring, FEC generation, or FEC regeneration. An admin changes this setting to trade off link error resilience against latency and interoperability, for example enabling FEC generation when the far end can decode it, or leaving it at the default of no FEC for compatibility with equipment that doesn't support it. For example, setting xpdrFecMode to 3 (FEC Regeneration) would have the transponder both decode and re-encode FEC on a 16G service passing through, refreshing error correction end-to-end.