This enumerated value selects whether this network element sends the older 1-bit RDI-P (Remote Defect Indication, path-level) or the newer 3-bit enhanced RDI-P, defaulting to onebit for compatibility with older equipment. An admin cares because, like the VT-level RDI-V setting, mismatched RDI-P formats between path endpoints can misrepresent defect status upstream, so this needs to be coordinated with the remote NE's capabilities. For example, upgrading both ends of a SONET path to threebit RDI-P allows more granular path defect reporting than the 1-bit default supports.