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

Re: ISSUE-54: doctype-legacy-compat

From: Sam Ruby <rubys@intertwingly.net>
Date: Sun, 25 Jan 2009 05:48:02 -0500
Message-ID: <497C4362.3000107@intertwingly.net>
To: Julian Reschke <julian.reschke@gmx.de>
CC: Henri Sivonen <hsivonen@iki.fi>, Robin Berjon <robin@berjon.com>, Larry Masinter <masinter@adobe.com>, HTML WG <public-html@w3.org>

Julian Reschke wrote:
> 
> 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.

What about XHTML5?

>> 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.

All of this input may be useful to the editor, and I expect that he will 
take it all into account.  Unless I missed it, I don't see any "can't 
live with" problems identified by either Henri or Julian with any of the 
URI schemes mentioned above.  So unless I hear otherwise, I expect that 
both of you will be willing to live with whatever the editor may decide.

> Best regards, Julian

- Sam Ruby
Received on Sunday, 25 January 2009 10:48:36 UTC

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