Not sure about what you are referencing here either. If your trip cancels or you receive a reassignment trip (RAT) it should fall under substitution, and can you can choose to accept or reject it (with loss of pay)...
Eligibility for Substitution
A pilot is eligible for substitution if he is removed from a trip for which he is entitled to trip guarantee for any of the reasons listed in this paragraph. Pilots in MUV, MUS, CMU, AFB, VLT, DRF or reserve are not eligible for substitution. If a pilot is removed from a substitution trip for any of the reasons listed in this paragraph, he shall remain eligible for substitution based upon his original trip (i.e., the trip or series of trips that actually created the substitution eligibility), The following events generate substitution eligibility and, where noted, reassignment offers prior to substitution.
Trip Canceled
The trip is canceled for any reason; or
If a trip is canceled due to a change of gauge a pilot shall be offered the rebuilt trip for his aircraft as a SUB or RAT, if possible.
Trip Rescheduled Outside 4 Hour Window
The trip is rescheduled to begin more than 4 hours prior to its original showtime or to terminate more than 4 hours after its original termination time. Trips in this category must be offered to the pilot as a reassignment trip prior to the pilot being placed in substitution.
Showtime Moved Up Without Notice
The trip is rescheduled with a showtime at least 1 hour earlier than the original showtime and the pilot is not adequately notified of that change. For purposes of this paragraph, adequate notification occurs if:
the pilot checks in at or prior to the new showtime; or
he is notified of the change at least 8 hours prior to the new showtime; or
he is transiting his base on separate trips not interrupted by a legal rest period and he is notified of the change prior to the new showtime.
Weather Restrictions
The pilot is removed from the trip due to weather related restrictions.
FAR or Other Governing Authority
The pilot is removed from the trip because he will or is projected to exceed FAR limitations or because of other government controlled restrictions, (e.g., work visa not issued in time, revocation or denial of route authority).
Contract Limitations
The pilot is removed from the trip:
because he will or is projected to exceed limitations contained in this Agreement (e.g., precautionary weather pull);
because the Company has determined that he is ineligible to fly based on a general, uniformly applied set of criteria (e.g., lack of LCA on route familiarization segments); or
due to other circumstances expressly specified in this Agreement as giving rise to substitution eligibility.
Operational Conflict
If a trip is revised more than 24 hours prior to the showtime for that trip, and it causes a conflict with a subsequent trip, the revised trip shall be dropped and eligible for substitution. If a trip is revised within 24 hours of showtime, and the revision causes a conflict with a subsequent trip, the subsequent trip shall be dropped and be eligible for substitution, unless the first trip is eligible for substitution for some additional reason.
Training
The pilot is removed from the trip due to his recurrent training, other than as a phase-in conflict (See Section 25.F.1.c.).