loadChange

How many loads this stop is planned to add to the vehicle: +1 for a collection, -1 for a delivery, 0 for a stop that carries nothing either way.

A planning figure rather than a promise, and the distinction matters for an action whose effect depends on what it finds when it arrives -- a stop that boards everyone waiting boards a number nobody knows in advance. Such an action declares 0 and is planned as though it changed nothing, which is the only honest thing a planner can be told; the capacity is then enforced where it is actually known, by the manifest, at the moment of boarding.