This TruthValue indicates whether ITU-T Y.1731 extensions (which add performance monitoring capabilities like delay and loss measurement on top of the base 802.1ag continuity-check framework) are enabled for this service. An admin checks this before expecting any of the DMM/LMM/SLM performance-monitoring objects elsewhere in this MIB to actually function for the service, since those extensions depend on Y.1731 being turned on here first. For example, a service with cienaCesCfmServiceY1731 set to 'false' would only support basic CCM continuity checking and fault detection, with any configured delay- or loss-measurement message settings having no real effect until this is enabled.