This tells the server to keep the session alive (typically for at least several hours) without sending or expecting tickles. This is useful in cases where our run queue procedure is not run regularly or at all, e.g. in text-mode shells.
The implementation here is geared toward compatibility with Netatalk and differs from Apple's published standards in a couple ways. It may or may not work with other servers.
It does this when the ASP layer gives a network error. To work around it, we count the number of sessions (possibly overestimating) and convert the error to "unable to open session" if PFI has not reached its session limit (8).
This is necessary because FIListSessions2 has a bug that causes it to return garbage in the server/zone fields for DSI sessions. (The bug is essentially that PFI is indexing into its own tables based on the ASP/DSI session number, rather than properly using a PFI-level session index.)
Stephen Heumann