When a library licenses a book from Bibliotheca or Overdrive, it shows up in the API as a book that has licenses (licenses_owned>0), but no available licenses (licenses_available=0). If our software were to deeply investigate this, it wouldn't make sense – how can there be no available licenses when no one actually has a loan on the book? But we don't investigate it, we just trust what the API says, and it works out. The book shows up in the SimplyE mobile app, people can place holds on it, and the holds will be serviced once the licenses actually become available.

When a library licenses a book from Axis 360, it shows up in the API as a book that has no licenses (licenses_owned=0). We treat this the same as a book that we don't own anymore. This means the book doesn't show up in the SimplyE mobile app and people can't place holds on it until it actually becomes available.

The Axis 360 API provides a book's publication date, and a book that's on preorder should have a publication date that's in the future. A simple solution would be to check for a publication date in the future, and on finding one, interpret licenses_owned=0 as licenses_owned=1. That would give Axis 360 titles the same behavior as Bibliotheca and Overdrive titles.