This indicates whether the tunnel group is configured to automatically revert traffic back to the primary tunnel once it recovers after a failover to backup. With reversion off, a tunnel that failed over to backup stays on backup even after the primary comes back up, requiring a manual switch back — a deliberate choice on some networks to avoid a second disruptive cutover right after the first one, at the cost of not automatically returning to the (often better-engineered) primary path. Tunnel group containing 'SEA-DEN-GW-01' might have reversion set to on(1), so once the primary path's fiber cut is repaired, traffic automatically switches back to it.