Library
Library loans
The copy, the borrower, and the date it is due.
A copy has a shelf and a state: in, out, or missing.
A loan is a borrower, a copy, and a due date. Return closes that loan.
A due list is the morning work. It is not a memory of who walked out with a book.
A reserve holds the next reader. The copy does not go back to the open shelf by mistake.
Fines, if you charge them, sit on the loan. The receipt is the same row.
The desk can find a title and say which copy is actually in.
A stock check is a section of shelves, marked against the register.
A new assistant can issue and return on the first afternoon.
Members, students, or staff are borrowers with a limit the desk can see.
The close of the day is loans out, returns in, and the copies still missing.