Re: [Cellar] Conversation about a NON-IANA request in Matroska

"Murray S. Kucherawy" <> Wed, 18 August 2021 23:07 UTC

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From: "Murray S. Kucherawy" <>
Date: Wed, 18 Aug 2021 16:06:52 -0700
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To: Spencer Dawkins at IETF <>
Cc: Francesca Palombini <>, Codec Encoding for LossLess Archiving and Realtime transmission <>
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Subject: Re: [Cellar] Conversation about a NON-IANA request in Matroska
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Hi there, sorry for the delay.

On Tue, Aug 10, 2021 at 10:18 AM Spencer Dawkins at IETF <> wrote:

> Hi, Murray, the backup expert reviewer for Media Types, and our
> responsible AD,

You flatter me.

Cellar is working on the Matroska specification, and one issue we've
> tripped over is that Matrosks implementations have traditionally used
> unregistered MIME types such as "video/x-matroska" and file extension
> ".mkv", which have never been registered in the Media Types registry, and
> (for extra credit) use "x-dash" notation that someone is likely to ask us
> to change, if we were registering something now.
> Specifically, the media types mentioned in
> have been in use for up to 19 years, and the sense of the Github discussion
> is that actually registering them now won't have much impact on anything.
> (You should be tagged in that PR, and that's where most of the discussion
> I've seen has happened)
> And we'd prefer not to start that conversation during AD Evaluation, IETF
> Last Call, or (especially not!) during IESG Evaluation and formal IANA
> review.
> As this work moves forward in the IETF stream, we wanted to ask, is this a
> thing we should talk with you about, sooner rather than later?

Well, glad you asked.

In the spirit of the media types registry, I'm inclined to say we'd rather
have something registered under what's perhaps a bit of a non-ideal name so
that people can interoperate from a common, registered reference, than not.
This is why the rules for the vendor tree are so loose.

So as your AD, I'd be prepared to argue in favor of registering the x-dash
name, and including a sentence or two about why we're making an exception
with respect to BCP 178 this time.  Of course, we can confirm with the
actual media type reviewers that I'm not crazy here.