While researching for Falldog's Guide to Gundam Canon and Timelines I was directed to this post by the great Mark Simmons on Mecha Talk back in 2007. In it he references a round table discussion from 2001 in Dengeki Hobby where folks from Sunrise discuss what's canon within the Gundam franchise. The website Mark linked to, at the time containing a transcript of the discussion, no longer exists. However, thanks to the Internet Archive Wayback Machine the content can still be accessed. In additional sections (which I didn't have translated) go on to reference other works and how they view them from a canon prospective. Mark's post on Mecha Talk does a good job summarizing the related content.
For my article on Gundam canon and timelines I went and got the primary section translated by Frog-kun. That translation is provided below for reference.
I asked Frog-kun for details regarding his translation of オフィシャル into canon and this is what he elaborated with,
"I translated the word オフィシャル (which is a Japanese transliteration of the English word "official") as "canon" a few times mainly to avoid repeating the same word over and over. If you don't think it fits, you can replace it with "official". From what I understood of the conversation, though, it did feel as if they were discussing official versus non-official continuity in a way that was very reminiscent of discussions about "canon" in the English fandom sense. I used the word because it would help put the discussion into perspective for an English reader.
"Also, you're right that Japanese fan lingo doesn't have a word like "canon", but there are words in everyday use like 本編 and 原作, which mean "original work". Discussions about what constitutes "official" work are still matters of contentious debate, and many Japanese fans hold the original work at a higher level of esteem than any subsequent adaptations.
"So yes, there was a bit of interpretation going on when I translated オフィシャル as "canon", but at the same time, I don't think the concept is absent in Japanese fandoms. "
What Sunrise Thinks is Official
Shibahara Hironori (part of the editorial staff at the Dengeki Hobby Magazine): Currently, there are things that people “don’t want to acknowledge” publicly or privately about a number of Original Mobile Suits. I’d like to talk about that today. But before that, what do you suppose is the definition of “official”?
Horiguchi Shigeru (producer at Sunrise, worked on Turn A, SEED Destiny, 0080, and Gundam Evolve): I count whatever’s in the footage as official.
Watanabe Toshihiro (works at Shindosha, a design office known for their mecha designs of Zeta Gundam and Gundam ZZ): We can roughly split the setting into three levels: White (official), grey, and black (lies).
Okazaki Akiyuki (writer): There are also “unusable” parts of the documents we use to make the setting, like how “the Rick Dias can enter the atmosphere” (1), which is part of what Sunrise “oversees”, if you want to put it that way.
Morita Akihiro (another producer at Sunrise): That was produced for the comic, wasn’t it?
Shibahara: But does that count as official canon?
Watanabe: Regardless of whether it’s part of the formal mythology or something that Sunrise oversaw, the basis of what counts as “official” is whatever is in the footage.
Okazaki: What about footage for the games?
Watanabe: They’re just game demos. At the start of Gihren’s Ambition (henceforth, Gihren), Ramba Ral gets off at New York, but it’s stated when he appears in Gundam itself that it’s his first time coming to Earth.
Shibahara: I think that Gihren has had a lot of influence. There are many people who are convinced that parts of Gihren as canon even when they’re not shown in the official material, except for the parts that are obviously “non-canon”, of course.
Ushimura Norihiko (producer at Bandai Games): From what I understand, the One Week War and the Battle of Loum at the beginning grabbed players’ attentions in particular.
Horiguchi: No matter how convincing it is, Gihren is simply a “what if” story. I’d like people to take it as a “picture that’s come to life” or a “film that was made after the war”. Something like that.
Okazaki: There are also problems in what appears in Sunrise’s footage. “Mobile Suit Gundam: More Information on the Universal Century” (2) was so problematic that you should take it as “rumours about what happened on the battlefield”.
Shibahara: The Gundam Ground Types were only ever criticised at first.
Watanabe: The real problem with The 08th MS Team was that there were already GMs around the time of “Gihren’s speech”!
Shibahara: It’s explained that the speech is a video broadcast and that they were sending test models into battle.
Okazaki: Gundam Ground Types are also mass-produced in this setting.
Horiguchi: Yeah, GMs weren’t being mass-produced at this time.
Watanabe: Oh, and by that time Sanders (Jr.) was already piloting a GM well-known as the “Shinigami”. (laughs)
Horiguchi: How strange. It’s supposed to be white, but we made the edges grey. The 08th MS Team is cruel. (awkward laughs)
Shibahara: Anyway, everything in the games is considered grey.
Watanabe: No, everything not shown in the anime is grey. It’s just that the cool things from the games got turned into Gunpla models.
Katagiri Keiichiro (designer): Like Char Gundam. (3) Gihren is black, which makes it interesting.
Kano Yoshihiro (works for Bandai Hobby): This (i.e. Char Gundam) is very black indeed.
Horiguchi: The models are fun to play around with because they’re not canon.
Watanabe: It’s an excuse to bring out the Gyan Cannons.
Kawaguchi Katsumi (works for Bandai Hobby): That’s clearly black as well.
Watanabe: The canon part of the setting is that Gyans and Gelgoogs are in competition, and lots of people play around with what-if scenarios, which flips the setting on its head.
Shibahara: What I can’t accept are the “High Mobility Type Gyans”. If they just exchanged their backpacks for mobility like the High Mobility Type Gelgoogs do, it’d be more believable.
Kano: Mobile Suit Variations and Gihren are a twist on the original setting, which puts them half in the grey zone, half in the black zone. For that reason, the things we (the Bandai Hobby department) develop are simply grey.
(1) A comic published in Gundam Magazine (Kodansha) had an episode about this.
(2) Supplementary footage to the The 08th MS Team OVA series. It shows short clips about the Gundam world.
(3) A mecha unit that appears in Gihren’s Ambition. When Char founds Neo Zeon as Casval Deikun, it’s possible to pilot a Char Gundam. Its proper name is the Casval Custom Gundam.