[Bug 13409] Defining Entity references for characters in XHTML.

http://www.w3.org/Bugs/Public/show_bug.cgi?id=13409

--- Comment #5 from David Carlisle <davidc@nag.co.uk> 2011-08-31 12:53:17 UTC ---
(In reply to comment #4)
> (In reply to comment #3)
> > It encourages the use of DTD that specify a syntax for previous versions of
> > (x)html which is going to be pretty confusing for users especially in
> > toolchains where the presence of a doctype triggers validation.
> 
> It's confusing, sure, but the Degrade Gracefully principle limits what the
> magic can look like.
> 

Since there was (and is currently) very little interoperability in how browsers
treated external dtd references in this situation, there is the possibility of
defining at least one form that allows the entities to be defined but doesn't
reference an obsolete version of html or mathml.

The current spec (and its implementation in Firefox 4+) are not compatible with
existing content, for example

http://www.w3.org/TR/MathML2/chapter3.xml


which as noted in comment #3 was compatible with Firefox [123] and is
compatible with IE9 (and doesn't give a fatal parse error in Opera 11.5 or
12.00 pre-alpha, although entities are rendered as & n b s p ; for both opera
versions)

Given that the existing implementations are not compatible with each other, or
the current wording, it is hard to argue that interoperability or even the
degrade gracefully principle would be greatly harmed by _allowing_ the entities
to be defined for <!DOCTYPE html>.

Conversely, in many XML toolchains (including IE's xml parser) specifying an
old dtd as required by the current wording will essentially corrupt the
document as the system will use that definition and so replace entity
references by their mathml2/xhtml1 definitions which are in a few cases (mainly
relating to unicode normalization or later additions to Unicode) different from
the definitions in html(5)/mathml3.

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Received on Wednesday, 31 August 2011 12:53:25 UTC