This read-only Unsigned32 (0..255) provides the received C2 signal label byte on the OCn Path, per its description. Administrators read it to see what payload type the far end is signaling for this path, such as identifying whether it carries VT-structured or concatenated payload. For example, a path expected to carry concatenated STS-3c payload showing an unexpected C2 signal label value would indicate a payload-type mismatch between the two ends.