- From: David Carlisle <davidc@nag.co.uk>
- Date: Fri, 23 May 2008 12:44:55 +0100
- To: ian@hixie.ch
- Cc: ap@webkit.org, public-html@w3.org, www-math@w3.org
The mapping currently defined for lang to 27E9 (MATHEMATICAL LEFT ANGLE BRACKET) is definitely the correct one and if the definition of rang is changed at all from its html4 definition it should be to this and not to U+3008 (LEFT ANGLE BRACKET) The original definition was to U+2329 (LEFT-POINTING ANGLE BRACKET) which is in the 2xxxx block of technical symbols not CJK punctuation, and the name "rang" comes from ISOTECH entity set for technical publishing. So this entity has always been intended for mathematical use. Unfortunately Unicode later specified a canonical mapping of this character to U+3008 which is definitely intended for CJK punctuation. This makes the U02329 character essentially unstable, and unicode have corrected their error as far as possible by deprecating that character and re-introducing a new one in the technical symbols block that is the same as the original U+2329 character but without the unfortunate canonical mapping to the U+3xxx range. So the character that is currently in unicode to support the intended usage of rang is U+27E9. However as Alexey says any change of definitionis likely to cause some pages to show missing glyph symbols, until font tables catch up. So not changing anything is another alterative that could be justified. Changing to U+3008 would be incorrect, it is precisely to avoid the association with U+3008 that Unicode introduced a new character. On balance I think HTML5 is right to change the entity definitions. Increasingly authoring software will generate documents just using character data (say utf8 encoded) directly and so rendering engines will get documents containing the "new" U+27E9 character whatever you (or I) do about the rang entity. Fonts will need to have updated tables, but In a world where new characters are still being added to Uniocde, and XML and HTML5 allow those characters to be used, there is always a danger that not all documents can be rendered on all systems. David ________________________________________________________________________ The Numerical Algorithms Group Ltd is a company registered in England and Wales with company number 1249803. The registered office is: Wilkinson House, Jordan Hill Road, Oxford OX2 8DR, United Kingdom. This e-mail has been scanned for all viruses by Star. The service is powered by MessageLabs. ________________________________________________________________________
Received on Friday, 23 May 2008 11:45:36 UTC