[webkit-dev] Fwd: HTML5 & MathML3 entities

[Maciej Stachowiak]

Forwarding this because it apparently didn't make it to the list.

Begin forwarded message:

> From: David Carlisle <davidc at nag.co.uk>
> Date: September 17, 2010 8:44:51 AM PDT
> To: webkit-dev at lists.webkit.org
> Cc: mjs at apple.com
> Subject: Re: [webkit-dev] HTML5 & MathML3 entities
> 
> Not sure I can post to this list (hence cc to  Maciej)  but replying to the thread from July
> 
> http://www.mail-archive.com/webkit-dev@lists.webkit.org/msg11986.html
> 
> there were a couple of points raised.
> 
> * that rang changed definition
> 
> and
> 
> * entities expanding to more than once character not being supported.
> 
> On the first:
> 
> rang did not used to be (directly) a CJK character it was in the math symbol block at 2329 but erroneously given a canonical decomposition to the CJK block at 3008. Unicode recognised the error but never change canonical decompositions so they deprecated 2320 and introduced a new character 27E8 that is the same apart from this decomposition.
> 
> http://www.unicode.org/charts/PDF/U2300.pdf
> 
> explicitly says these characters are deprecated:
> 
> 
> Also, even if Unicode had not deprecated 2329, the W3C "Unicode Normal Form" bans entities using characters that have canonical decompositions as it makes entity expansion and NFC canonicalisation interact badly. Changing the definition is unfortunate but sort of inevitable given the history.
> 
> 
> On the second:
> It's probably worth noting that currently the HTML5 spec only lists entities that expand to a single character, but there is an open bug entry about that:
> 
> http://www.w3.org/Bugs/Public/show_bug.cgi?id=10067
> 
> David
> 
> 
> 
> 
> 
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