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Re: ISSUE-54: doctype-legacy-compat

From: Lachlan Hunt <lachlan.hunt@lachy.id.au>
Date: Fri, 16 Jan 2009 16:03:17 +0100
Message-ID: <4970A1B5.8080104@lachy.id.au>
Cc: Sam Ruby <rubys@us.ibm.com>, HTML WG <public-html@w3.org>

Henri Sivonen wrote:
> <!DOCTYPE html SYSTEM "about:sgml-compat"> would seem to fit the 
> requirements as a legacy generator alternative to <!DOCTYPE html>.

Based on some further discussion in IRC, these are the advantages of 
using the SYSTEM identifier with an about: URI scheme.

* Many people are already familiar with the scheme and so it's
   memorable.  More so than, e.g., the tag: or data: URI schemes.

* It's shorter than an equivalent http: URI would be

* It's non-retrievable and so there's no expectation of a DTD.

* Use of an absolute URI rather than a string like "sgml-compat" that is
   indistinguishable from a relative URI prevents consumers that attempt
   to retrieve DTDs from getting 404s from many servers.

* Typing about:sgml-compat into browsers generally results in an error
   message or blank page. This helps in pre-empting any bogus
   rationalisations for why using this one with the URI is better than
   <!DOCTYPE html> without the URI.

* As Philip demonstrated earlier, using a SYSTEM identifer is generally
   more compatible with legacy producers than a lone PUBLIC identifier.

Lachlan Hunt - Opera Software
Received on Friday, 16 January 2009 15:03:55 UTC

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