This read-only on/off attribute, defaulting to off, indicates whether a Path-layer Remote Defect Indication is detected by the OC-3 port. It gives an administrator a more granular SONET path-level defect signal than the line-layer RDI, useful for isolating problems to a specific virtual tributary path rather than the whole line. For example, a technician seeing path-level RDI but no line-level RDI would suspect a problem specific to this port's payload path rather than the overall optical line.