Turnstile

These are the admissions the gates could not have caught while they were apart. Each names every gate that let it through, oldest first; the later ones are the copies.

Every gate that joins is handed the list, so an unknown code is refused without asking anybody. The codes carry a check character: a typo is "malformed", never "unknown".

Without a licence the gate scans exactly the same, and the night's file is stamped licensed:false. A trial whose file looked identical to a paid one would be worth less than no trial.