Reading my original post, perhaps I should have made the important point more clear. My question is about an ILS suitable for a library that does not own its books, but is borrowing those books from patrons. The books all have lease end dates associated with them. Book lenders are very similar to book borrowers, and they require end of day processing to see if any of the library's books are due back to them, in the same way borrower's books are due back to the library. So, in the last two posts which mentioned "simple borrowing", that is what I am wanting, but for the library to be simply borrowing the books AND for patron to simply borrow those same books out of the library. Book lenders and book borrowers are essentially the same, except lenders first check a book in, and the due date is when the book leaves the library, and book borrowers check books out and then back in again. Of course, many book borrowers are also lenders. Are any currently existing open source ILSs flexible enough to support this model? Sorry for the confusion, Elliot