This object indicates the status of optical transceiver-monitoring function for a SFP port. When a SFP with transceiver-monitoring capability is plugged in a port but the transceiver-monitoring function of the port is disabled, system will not detect the SFP's abnormal status but user still can check the current status via dDdmIfInfoTable.
Sources for this description
D-Link official switch MIBsD-Link MIB copies (LibreNMS/Observium Community)