On Jan 7, 2015, at 10:43 PM, Johnny Billquist <bqt at softjar.se> wrote: ...Note where I said "page structure" above. :-) I've read RFC 959 (as well as the various additions) backwards and forwards way too many times by now. The page structure would be a way of doing this. It will definitely not work with any other client out there. But on the other hand, I'm mostly interested in the efficient transport of files between two RSX systems for this part anyway, so it will be towards my own client only. But I doubt VMS does it this way, and I was curious about if I could possibly do something that would be compatible with VMS, since enough commonality in file storage exists between RSX and VMS for this to actually be useful. So the question is - what do VMS do when talking to another VMS system, and how does VMS decide when to use the extra abilities? If there isn t a spec, the alternative would be to capture an FTP session with a tool like Wireshark, and reverse engineer things. That tends to be a pain but it can be done if all else fails. paul