Hi Pierrick, I'm glad to hear you're looking closely at reserves. It's something that our library really depends on (as you can tell from all the bugs I've filed). I'd be great to get the reserves system tightened up.
1. A reserve can be linked to a biblio or to an item.
I know you're talking about the workings of the script here, but here's what we'd like to see at the other end: At NPL we'd like patrons to be able to reserve at the biblio level, and librarians to be able to reserve at either the biblio level or the item level. Our patrons don't have a need to reserve a particular barcode. To make that feature available to them would only be confusing. But librarians might need to reserve a particular item because of damage, for instance, or a missing CD from a set, etc.
When trying to issue an item reserved, only the first reserve is displayed for confirmation of cancel and only the first reserve is cancelled if asked by the librarian, without changing the priority of other reserves. I think it's a bug of course.
3. Finally, I really don't understand why Koha ask for reserve cancellation when issuing.
Perhaps this issue comes up more at a public library. We're very familiar with this situation: A woman places a reserve on a book, and when it arrives she sends her husband in with his card to check out the book. We issue the book to the husband and when Koha prompts us we say yes to override and yes to canceling the reserve (because the wife's reservation is being fulfilled by the transaction to her husband). In this case, /only/ the first (highest priority) reserve is relevant, so it's proper that only the first reserve is displayed. -- Owen