Re: XML Blueberry (non-ASCII name characters in Japan)

[Elliotte Rusty Harold <elharo@metalab.unc.edu>]

At 12:30 PM -0400 7/9/01, Simon "St.Laurent" wrote:

>While I spend a lot of time trying to prevent things which are piled on
>top of XML (W3C XML Schema, XInclude, XML Base, even Namespaces) from
>being considered "XML", I don't see any reason that XML itself must
>remain fixed while the foundation on which it is built moves.
>
>Unicode is the rock on which XML is built.  When the rock moves, XML
>should move.
>

Not necessarily. The rock hasn't moved. It's grown. That's a very different thing. 

XML is built on Unicode 2.0 with explicit consideration of how future variations in Unicode will change it. The decision built into the XML spec was to allow all possible Unicode characters that might ever be defined to be used in Unicode documents as text. A decision was also made not to forbid undefined Unicode characters in text. This allows Unicode to grow (not move) quite dramatically without affecting XML.

A different decision was made for name characters. There it was decided that these would be based on Unicode 2.0, and that code points which might be assigned in the future would not be allowed as name characters. I'm not sure that decision was right, but I don't think a convincing argument for revisiting it now has been made yet. 

Perhaps the most important decision made in XML 1.0 relative to all this was to explicitly list which characters would be allowed where in the BNF grammar rather than normatively referencing various Unicode character classes. In essence, XML 1.0 copies Unicode with some modifications rather than building on top of it. Even if Unicode did something as radical as shuffling the code points for the different characters, that wouldn't mean that XML had to change. 
-- 

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| Elliotte Rusty Harold | elharo@metalab.unc.edu | Writer/Programmer |
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