The id of the gear item being moved.
The destination container id; empty/null/undefined means "On Body".
Every gear item on the actor, each with its current containerId.
Whether the move is allowed, whether it changes the container, and the normalized destination.
Decide whether a gear item may move into a destination container, and whether that changes its current container. Rejects dropping a container into itself or into any of its own descendants, either of which would form a containment cycle. Containment is by reference (
system.containerId), so "On Body" is the absence of a container — an empty,null, orundefineddestination.