This CoriantTypesYesNo switch (default no) makes the coherent optical channel (och-os) on the line side of a pluggable transceiver shut down its transmit laser whenever the overall service in that direction suffers a signal failure, a behavior mainly used at regeneration nodes to propagate the failure onward as a visible loss-of-signal. An administrator enables this at intermediate regeneration sites so a failure detected on one segment doesn't get silently regenerated and hidden from the next segment downstream. For example, enabling propagate-shutdown on och-os at a mid-span regenerator ensures that if the upstream half of the path fails, the downstream half also sees a clean loss-of-signal instead of continuing to transmit as though nothing were wrong.