This OID holds the Trail Trace Identifier (TTI), up to 15 characters, that this WAN 10G SDH interface transmits in its outgoing signal overhead, applicable when the parent card is configured for TDM switching. Setting a distinctive transmit trace lets the far-end equipment on the SDH path verify it is receiving from the correct source, providing an automated cross-check against fiber misconnections. For example, an operator might program this object to transmit RING1-EAST so the receiving node at the far end of the SDH ring can confirm, via its own expected-trace setting, that it is connected to this interface and not a different span.