Interesting DP I just had this week. I was rebooked on RNO->BUR->OAK when my RNO->OAK direct flight was cancelled after sitting on the plane for an hour. Got A36-A37 for me and companion the BUR->OAK leg, but others who were rebooked on the same flights got B boarding positions. Plane was not completely empty, so those boarding positions appear to be recycled/reused. So boarding positions can still be recycled during IROP?