This is the name of a manually-configured co-routed bidirectional GMPLS tunnel -- one where the forward and reverse LSPs are required to follow the identical physical path in both directions, unlike the separately-tracked associated tunnels seen elsewhere in this MIB. An admin names these distinctly from unidirectional tunnels to make clear at a glance that this entry represents a full round-trip path with guaranteed-symmetric latency, a property some services (like TDM circuit emulation) specifically require. For example, a name like corouted-tdm-circuit-14 signals this tunnel exists to support a service that depends on forward and return paths being identical.