This read-only octet string, up to 32 bytes, is the expected operator-identifier portion of the trail-trace identifier (TTI) for this ODU. This lets a multi-operator network validate that a wavelength or ODU path genuinely originates from the operator it is supposed to, which matters on shared or leased infrastructure. For example, oduExpOperator set to a specific carrier code not matching the received operator TTI would indicate the circuit is unexpectedly terminating on a different carrier's network segment than planned.