The following is what constitutes a reroute, how reroute pay is calculated is pretty much greek to everyone I know....

"Reroute” means:

a.
alteration of a pilot’s rotation or portion thereof due to irregular operations to:

1) delete a previously scheduled flight segment(s), and/or
2) add a flight segment(s) that is not open time (including flying removed from open
time). or

b.
alteration of a pilot’s rotation or portion thereof to:
1) delete a previously scheduled flight segment(s), and/or
2) add a flight segment(s) under Section 23 N. 21. or O. 15.;
and

c.
notification to the pilot, after the airborne departure of his first flight segment, of such alteration.

Note: An alteration in the departure, enroute or arrival time of a scheduled flight segment does not constitute a reroute.

Denny