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   Re: [xml-dev] Errors in Kendall Clark's xml.com article on QNames

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At 1:50 PM +0000 2/13/02, Henry S. Thompson wrote:

>2) "..there's no way for an XML processor to tell whether QNames are
>    used in values." (again, quoting Lenz [2], ellipses in original)
>That's simply false -- any sensible use of QNames would involve a W3C
>XML Schema or other type-assigning schema language, which in turn
>would identify all element content and/or attribute values which were
>QNames.  This means that using type-aware XPath 2.0 it would be
>trivial to locate all QNames in a document.  Note further that any
>sensible API for type-information-bearing infosets will expose the
>_values_ of leaf nodes, which for QNames is defined as being a pair of
>namespace name and local name.

No, that's simply true. Many of us aren't using schema-aware parsers. 
Most of us who are still don't have access to the PSVI type 
information in our applications. Even if we did, most of the 
documents we get in practice wouldn't have schemas.

QNames in attribute values and element content are a huge mess and a 
big mistake. I've seen them complexify virtually every significant 
system I've worked on that had to process arbitrary XML documents. 
They were a problem for JDOM. They were a problem for XInclude. They 
were a problem when using DOM and SAX. They make XML significantly 
more complex.

| Elliotte Rusty Harold | elharo@metalab.unc.edu | Writer/Programmer |
|          The XML Bible, 2nd Edition (Hungry Minds, 2001)           |
|              http://www.ibiblio.org/xml/books/bible2/              |
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