So, you may or may not have heard of Project Heimdall. It's a "collaborative writing project" created a year before canons were a thing by Hornby, with the theme of the Foundation's preparations for and interactions with extraterrestrial intelligences. It has 5 tales by 4 authors in addition to the hub, as well as 4 skips set in its universe by an additional 4 authors.
Now lets look at the requirements for something to be a canon:
A minimum of five tales written.
check
A minimum of three authors writing the tales.
check
Your canon cannot be "closed" to other, new contributors.
From the hub page: "Who can participate in Project Heimdall?
Anyone! If something strikes your fancy, write it up."
Your canon cannot be "finished."
The hub makes no mention of an end goal and in fact implies a lack of such via Hornby's thoughts on the endless number of episodic storylines that could fit into the project.
So, this should be a canon. As far as I can tell, the only reason it isn't already is because its older than canons as a concept and Troy forgot about it/didn't know about it when he was making the canon hub for the entries of the new years canon contest in 2013. Here is a post from Roget all the way back in 2014 that proposed making it a canon as a part of a tag revamp, a notion seconded by Eskobar. However, the thread was derailed by Aelanna and nothing was done regarding Heimdall's status.
I brought this up in 17 a week ago and was told that it wouldn't be considered a canon because Hornby didn't name it a canon, even though canons didn't exist at the time and this was pretty expressly the exact intent of what a canon was. ARD did tell me that I could start a discussion on the subject, hence this post. However, precedent here as well as Hornby's own statement in the hub that "he's not "running" things in any sort of formal, moderating, or administrative way" suggests that it shouldn't matter whether it was proactively declared a canon by its inactive creator. Rather, we should recognize it fits both the stated requirements and the express spirit of a canon, and feature it on the canon hub so that it can attract the notice it deserves. I pmed Hornby for his input a week ago, but he didn't respond.
(side note: while looking through the tag masterlist to make this post I noticed the Resurrection tag was listed under tale series instead of canons, someone with permission should probably fix that.)