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

Re: ISSUE-54: doctype-legacy-compat

From: Julian Reschke <julian.reschke@gmx.de>
Date: Sun, 25 Jan 2009 10:51:12 +0100
Message-ID: <497C3610.40305@gmx.de>
To: Henri Sivonen <hsivonen@iki.fi>
CC: Robin Berjon <robin@berjon.com>, Larry Masinter <masinter@adobe.com>, HTML WG <public-html@w3.org>

Henri Sivonen wrote:
> ...
> Thus, "about:sgml-compat" is *not* interpreted as a URI by any 
> conforming HTML5 consumer. In my opinion, it is therefore unnecessary 
> for it to be of the form of a URI in a registered scheme.
>
> The point of making it *look* like an absolute URI (i.e. have a colon in 
> the magic string) is to avoid useless GET requests to URIs relative to 
> the document URI in a situation where a piece of software goes and 
> dereferences the magic string as if it were a URI.
> ...

Existing software expects a URI-reference here 
(<http://greenbytes.de/tech/webdav/rfc3986.html#rfc.section.4.1>), so 
yes, it's good not to use a relative-ref, but similarly, it's also good 
to use a registered URI scheme if we choose an (absolute) URI instead.

> The point of suggesting "about" as the string before the colon was that 
> due to pre-existing special use in browsers, it won't be feasible for 
> anyone to register "about" as a URI scheme for another purpose.
> 
> The 'tag' URI scheme is less suitable, because 'tag' URIs by their 
> nature include non-mnemonic strings which make them harder to memorize. 

I don't see why that is a problem. The *only* reason why we're 
introducing this doctype variant is to get rid of validator warnings. So 
I would expect those who use it to properly type it, otherwise they'll 
notice.

> Furthermore, the date in the 'tag' URI scheme is dangerously close to 
> being a version number, and one of the design goals was to avoid putting 
> anything that resembles a version number into the doctype.
> 
> The problem with 'urn' is that there are actual URN resolvers that map a 
> subset of URNs onto dereferencable URIs. Even if the 'w3c' URN scheme 
> went nowhere, finding out that it goes nowhere could still cause waste 
> in theoretically possibly scenarios. Using about: addresses even that 
> mostly theoretical case.

That's *very* theoretical.

For instance, the urn:uuid: scheme is used all over the place (yes, not 
in HTML pages). As far as I can tell, it hasn't caused any problems yet.

Best regards, Julian
Received on Sunday, 25 January 2009 09:51:56 UTC

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