Question
How soon should I report a bicycle kept in the hall?
Report a bicycle kept in the hall as soon as you know about it. The conditions ask for a report without delay, and in practice that means the same week rather than the same hour.
A bicycle in a communal hall is in the home and not quite in it, and the schedule says which of the two the policy treats it as.
The frame number is stamped under the bottom bracket. It is the detail that makes a bicycle a specific bicycle.