refusal
Why this zone would refuse a claim from claimant, or null when claimant could take it.
The question a modeller has to be able to ask, and the reason it is answered here rather than left to be worked out: getting it right needs three facts in the right order and the claimant's own identity, and a hand-written version will get the last part wrong. A zone reserved for a closure refuses a stranger and admits both the holder it was promised to and a vehicle escaping an older reservation -- so "is this zone reserved?" is not the same question as "would it refuse me?", and only the second one predicts what happens.
claim is this same function, which is what keeps the two from drifting. A check that disagreed with the claim it predicts would be worse than no check at all.