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Re: [xml-dev] Support for XML 1.1?

On Mon, 2012-10-01 at 16:06 +0000, Costello, Roger L. wrote:
> Hi Folks,

> 
> It appears that using XML 1.1 is the best way to go for supporting all
> the US-ASCII characters.

No.

XML 1.1 is based on Unicode, as is XML.

US ASCII contains 128 defined code points (it's a 7-bit standard, with
the 8th bit available, if present, for parity checking).

Of these, the "c0 controls" with the exception of tab, carriage return,
newline, are deprecated [[
Document authors are encouraged to avoid "compatibility characters", as
defined in Unicode [Unicode]. The characters defined in the following
ranges are also discouraged. They are either control characters or
permanently undefined Unicode characters:
]]
and, like C1 controls, may only appear if escaped as character
references.

In practice, the only feature from XML 1.1 that you miss in using XML
1.0 5e instead is actually namespaces 1.1 and the ability to remove the
association between a prefix and a URI. The other "significant" feature,
adding Unicode NEL to whitespace, was for sure a mistake, and I'm not
sure it's actually being used outside one or two organizations.

As others have said, 1.1 did not get industry traction.

One reason cited was that it could potentially change the meaning of
existing documents, because of NEL in attribute values turning into a
space during normalization, and another was that existing XML 1.0
documents that had been well-formed became non well-formed if they used
the C1 control characters without escaping them.

But the biggest problem was a revision to XML 1.0 that said a processor
should reject documents marked as being XML 1.1. So it's too risky to
send an XML 1.1 document over the net. We retracted that mistaken
assertion, but it was too late.

Liam

-- 
Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/
Pictures from old books: http://fromoldbooks.org/
Co-author: 5th edition of "Beginning XML", Wrox, July 2012



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