Subject: RE: [xsl] Attributes with default namespaces? XSLT Rec question.. From: "Michael Kay" <mike@xxxxxxxxxxxx> Date: Fri, 14 Nov 2008 09:56:46 -0000 |
> It isn't very explicit about why the default namespace does > not apply to attributes, though. And indeed REC-xml-names > itself neither. > > Is there anyone on this list who happens to know what the > real reasons where why that rule was added to that > recommendation? Not that I object, it saves typing a lot of > prefixes on occasion. I am just being curious. :-) It can be hard to work out why a WG has made a decision even when you were at the meeting. There was a lot of debate about this: I think the three options were that unprefixed attributes should be (a) in no namespace, (b) in the default namespace, or (c) in the namespace of the containing element. The underlying principle is that most attributes are defined as part of the same vocabulary as the containing element (a "vocabulary" being a unit of design and change control). You don't want (b) because that means if you give the element a prefix you have to give most of its attributes a prefix too (<html:table html:width="10" html:height="30"/> gets pretty ugly). The choice between (a) and (c) is more arbitrary, but (a) reflects that the definition and semantics of the attribute are usually local to the element; the fact that a height attribute is defined for an html:table element doesn't mean you can use it (in the form html:height) on an invoice element. This also explains the idea that "no-namespace" names are not in a namespace - the thinking is that a namespace has a definition, it is controlled by a design authority, whereas the no-namespace is a bucket in which anyone can put anything. While this idea has merit, the language of a lot of specifications would be simpler if the "no-namespace" were treated as just another namespace that happens to have no name (or a name of ""). Michael Kay http://www.saxonica.com/
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