You get straight pay for the value of the trip. (Single pay)

You don't get credit for the purpose of filling up on reserve or meeting the green slip trigger.

For example if you are rerouted and you are eligible for RR pay on the last day you would get single pay credit for the entire trip plus single pay no credit for the reroute last day. Assuming that it is 5:15 they would be pay but not count for reaching the GS trigger if you are under the threshold.