Re: [xml-dev] Lesson Learned: Use namespaces for both markup anddata

[Evan Lenz <evan@evanlenz.net>]

I think that hits the nail on the head. Use QNames in content (or 
attribute values) only if you're referring to objects already identified 
by QNames. This is most appropriate for XML that describes some other 
XML, e.g., <xsd:element> or <xsl:element> or XPath expressions. In each 
case, yes, QNames are used in content, but they're referring to (or 
declaring, or constructing) *elements*.

Things get nasty when people start using QNames for everything under the 
sun, not just elements and attributes and references to them. This 
practice was blessed with XSLT's use of QNames for auxiliary objects 
(mode names, variable names, etc.), and then W3C XML Schemas joined the 
party, using QNames to name data types, groups, attribute groups, etc.

This in turn puts the burden on other people to use QNames when 
referring to such objects. Someone has to come in and say, "Enough!" No 
more QNames for new kinds of things. Let's grandfather in what's already 
identified by QNames, and if you need to refer to them, use QNames, but 
please don't use QNames for modeling your own data.

Evan

Michael Kay wrote:
>
> If the objects you are referencing are identified by QNames (as XSD 
> types are), then you should certainly use QNames when referring to them.
>  
> But that doesn't mean all objects should be identified by QNames.
>