Several parties have expressed interest in adding ILL functionality on the mailing list. This page could be a place to collect ideas and documentation.
Since there are lots of different ways to implement ILL it seems like a viable solution to identify some core functionality that needs to be in place for everyone, and then let that core be extended to handle different protocols, standards etc.
Some easy way to create records that are hidden in the OPAC but enable lending, fines etc
Allow borrowing and lending across multiple systems according to rules set by individual library systems or consortia (e.g. my patrons can view items from (and borrow from) these 15 Koha libraries and that Evergreen consortia during the summer months but only the 15 Koha libraries during the winter months)
Staff should not have to create temp bib records or temp patron records to do any internlending transactions. Either the patron and item databases are shared/combined in a way that makes this unnecessary, or the system injects the proper records from the borrowing system to the lending system automatically.
Maybe think of it more like a materials request sent to a branch within a single system (I've heard this called a pending list and a router). The request can be accepted by lender (e.g. like hold being triggered within a single system) which would create whatever records were needed in both systems so the transaction could be tracked and all other requests for that item would be cancelled. First to claim the request wins so as not to slow down the process with sequential requests (like OCLC).
Features for unmediated ILL transactions (including INN-Reach/Link+ compatibility, support for SIP2 for legacy systems, etc.)