W3C home > Mailing lists > Public > public-html@w3.org > February 2009

RE: ISSUE-4: Versioning, namespace URIs and MIME types

From: Larry Masinter <masinter@adobe.com>
Date: Wed, 18 Feb 2009 20:49:21 -0800
To: Ian Hickson <ian@hixie.ch>
CC: HTML WG <public-html@w3.org>
Message-ID: <8B62A039C620904E92F1233570534C9B0118C86595CF@nambx04.corp.adobe.com>
I said:
> I'm discussing whether there is to be a standard way of indicating which 
> mode is intended or desired

Ian replied:
> Doesn't HTML5 already define the standard methods for user agents to 
> determine which mode to use? I'm confused.

We've gone over this difference in perspective multiple times:
* The question was about a "way of indicating" (for authors);
* the reply was about a "methods for user agents" (for browser
 implementers).

The difference between the question and the reply is whether the
way of indicating versions is part of the conforming "language"
(it isn't now) and whether there is useful guidance for authors 
or producers (there isn't now).

Does this help with the confusion?

> The DOCTYPE axis and version attributes can't be used for triggering 
> modes, since they're not available in the example I gave in:
>   http://lists.w3.org/Archives/Public/public-html/2009Feb/0375.html


a) To repeat: "Insufficient" is different from "not useful". DOCTYPE
   can be useful when it is present, even if there were cases which may
   need some other mechanism.
b) "mode inheritance" for scripts executed within modal implementations
   would allow DOCTYPE or version attribute or element indicators to
   disambiguate the intended mode of a script-created document.
   

> (Unless you are talking about modes that are intended to be non-conforming 
> and not used, in which case they don't need to be available. This is the 
> case with the quirks and limited-quirks modes we have currently.)

It's an illusion to document and specify a mode and then label it
"non-conforming and not used". Interpretation modes in receivers
are dialects in senders. If you have modes, you have versions.

> I wouldn't consider MIME registrations a success story. I certainly 
> wouldn't consider them evidence that versioning is a good thing. They are 
> at best inconclusive on the matter, IMHO.

The 16-year-old discussion I pointed to was specifically about
the relationship of MIME registration and versioning, and
as a counter to your apparent dismissal "we discussed this two 
years ago". Just pointing out that the discussion has been
around for more than two years.

While there are certainly problems with MIME registration, on the
whole MIME has been extremely successful. The discussion in 1992
supports with your recent rediscovery that, in general, versions 
are undesirable; however, it is also given that versions are
inevitable, and it is better to have explicit in-band indications
of intended version than it is to assume some other weakly specified
inference process or out-of-band communication.

Do you have any examples of why this advice was bad for any
data format other than HTML, or examples of any languages
or formats (other than HTML) used in distributed communication
where there are multiple incompatible versions or modes
and no explicit indication of version?

Regards,

Larry
-- 
http://larry.masinter.net
Received on Thursday, 19 February 2009 04:50:02 UTC

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