This OID holds the expected Trail Trace Identifier (TTI), up to 15 characters, that this WAN 10G SDH interface is configured to compare against the trace actually received on the incoming signal. SDH's trail trace mechanism continuously embeds an identifier in the signal overhead so equipment can verify it is connected to the correct far-end path; a mismatch between this expected value and the received trace signals a possible misconnection. For example, if this expected TTI is set to SITE-A-RING1 but the received trace shows a different string, the interface can raise a trace identifier mismatch condition warning the operator that the fiber may be cross-connected to the wrong path.