I was going to have a look at implementing this proposal as an import/export format for my feedreader this weekend, to see what issues might arise, and it immediately occured to me that there were a few things missing from the spec.
If you want people to be able to use this format as an alternative to OPML, I think most of the following are fairly essential.
1. A file extension for Windows users and possibly a file type code for Macs (not being a Mac user, I don't know how important that is).
2. A media type for browsers. I see there was a mention of MIME types in your table of contents, but no mention of it in the spec itself, possibly because the original intent was to use the Atom media type.
3. A catchy name, so websites can identify the format that they're offering for download and feedreaders can include an "Import From XXX" menu that will mean something to users.
4. An identifiable icon, both for websites offering this format for download, and to represent the format when you have bunch of these files lying about on disk.
Not that having all of the above is going to guarantee you widespread adoption or anything, but without these things you'll be making it a whole lot harder for people to use the format.
Regards James
