Our specialist ATSAs will be able to answer your queries about the system, where to find information on the system about routing and addressing and any other APFEx related queries.
From the little I've seen of it, the AFPEx system is a technical implementation of any ATS messages that used to be carried over AFTN. The layer that seems to be missing in terms of info (and that may just be bcause it's early days) is who sends what messages when.
I'm reasonably literate when it comes to this sort of stuff, and I can get my head round an FPL, DLA and CHG and even the ATFM set (SMM, REA, SPA, SRJ, FCM, RJT, SWM, RFI) because they're documented by CFMU. But I'm not sure I'd know if and when I should send a DEP, ARR, CPL, EST, CDN, RCF, SPL ... Is that something I'm going to need to understand if I use AFPEx?