The Cache case lies between Static and Reroute,
- It will look at the static file pointed by the URL. If it exists and is validate, serve it (including a proper authentication).
- If it is expired as indicated by the Expire parameter, the stale cache will be deleted.
- If it is deleted, or not existing, an internal URL will be rewritten in the same way as Case=Reroute.
- At the end of standard serving, a new cache will be written onto disk.
Because the cached page is unknown beforehand, and its status is only setup at the time of hit, we call it Schrodinger Cache, matching to the famous Schrodinger Cat experience in quantum theory.