This CoriantTypesOtukFec value (default G709) selects which forward error correction scheme an OTU2e (enhanced OTU2, roughly 11.1 Gb/s) trunk carrying an oversized client signal such as 10GbE LAN applies to the OTUk frame wrapping the client signal, applicable when the port is a client or client-subport. An administrator selects the FEC type to match interoperability requirements with the far-end equipment and to control how many bit errors the link can correct before the signal is judged failed. For example, leaving OTU2e at the standard G.709 FEC ensures compatibility with legacy far-end transponders that only support the base ITU-T correction scheme rather than a proprietary enhanced FEC option.