This identifies an OAM Loopback Test on a VPL, VPC, VCL, or VCC termination point, using a segment OAM cell. The test type must have appended to it a code that uniquely identifies an intermediate point responsible for looping back the cell. If this is absent, the loopback is performed at the end of the segment or connection. E.g., the OID { atmfM4TestOAMLoopbackSeg 5 } identifies that the loopback should be performed at the intermediate point labeled 5.