This object indicates whether tunnel reversion is turned on or off for this static encap tunnel, as the description states. With reversion on, once a failed primary tunnel in the group recovers, traffic automatically switches back to it after the configured hold timer rather than continuing to ride whatever backup took over -- a design choice that trades a brief second cutover against always running the intended primary path. For example, an admin might deliberately set this to off if the primary tunnel has been flapping, so traffic stays on the stable backup instead of repeatedly bouncing back to an unreliable primary.