So, I thought I'd try a poll. :D
When I am talking about the novels, animated series, comics, web extras, role-playing games, audio dramas, and so on that are authorized by a particular fandom's owners but are not part of main canon, I call them:
just plain non-canonical
Better than canon, usually
Expanded Universe/Extended Universe/EU
authorized fanfic, or something else involving the word 'fan'
Different terms in different fandoms, and I'll go into detail below
I am going to talk about this in a comment.
This concept needs a fanlore entry of its own.
If there's a fannish term I use a lot, and a few of my friends do, and I really find it useful, but hardly anybody else uses it, I should:
Try to avoid using it on Fanlore and similar places
Use it on fanlore, and hope somebody else decides to make an entry for it eventually
Make an entry for it (or add it to the relevant entry) in hopes that it will become more widespread
ETA: I am also interested in whether people include things like interview canon and behind-the-scenes extras, drafts and outlines and subtitles, things someone involved with the production once said informally, prop canon, and merchandise packaging under the same umbrella as authorized media tie-ins, or consider them a different level of canon, and whether different terms include different things to them. But I couldn't figure out how to phrase it as a poll question in a way that wasn't overcomplicated.
People are invited to add comments expanding on this!