This attribute is the type of test to be run. The available test types include the following: card test sets up an internal loop on the board and runs a bit error rate test. manual test assumes the line is looped back externally and a bit error rate test is performed. localLoop test loops back the local modem and performs a bit error rate test. remoteLoop test loops back the remote modem (or CSU) and performs a bit error rate test. externalLoop test loops back the line to the far end. payloadLoop test only loops back the payload data received from the incoming line. remoteLoopThisTrib loops this particular tributary back at the far end, using services provided by the parent. v54RemoteLoop initiates a V.54 Remote Loopback test. pn127RemoteLoop initiates a PN127 Remote Loopback test. Note that not all test types are not supported by all function processors.