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   RE: [xml-dev] Dilemma: dot notation or attribute

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Why don't you use namespaces? This seems to be exactly what they were designed for. 

	-----Original Message----- 
	From: Autumn Cuellar [mailto:a.cuellar@auckland.ac.nz] 
	Sent: Sun 9/22/2002 10:16 PM 
	To: xml-dev@lists.xml.org; XML-L@LISTSERV.HEANET.IE 
	Subject: [xml-dev] Dilemma: dot notation or attribute

	I'll try to explain my dilemma as briefly as possible and maybe you
	could offer suggestions.  I want to be able to import one document with
	the root element <model> into another document with the same root
	element and then access element content in the imported "model".  We've
	considered two ways of doing this.
	The dot notation method:
	   <import_model name="example"
	        uri="http://www.example.com/sample_model.xml"; />
	   <variable name="A" units="example.meter_per_cm2"/>
	The above method effectively aliases "example" to the sample model uri,
	and then the variable can reference units defined in another model by
	listing the model nickname and the units separated by a dot.
	The attribute method:
	   <import_model name="example"
	        uri="http://www.example.com/sample_model.xml"; />
	   <variable name="A" units="meter_per_cm2" units_model="example" />
	The attribute method is similar, however, the imported model is
	referenced via a specific attribute.
	Neither method is exactly XML-happy.  You expect the attribute value to
	be a literal value with no hidden meaning for a processor to detect, as
	would be necessary with the dot notation.  However, there have been
	instances where groups give certain meaning to parts of an attribute
	value.  XML Schema uses the xsd: namespace prefix in attribute values to
	indicate that data types have already been defined by the XML Schema
	language.  And the attribute method bothers me because the "units_model"
	attribute is qualifying another attribute instead of the element it's
	placed on.  I've never seen another XML language do this before.  Does
	anyone know of a standard case in which an attribute describes another
	Do you have a preference of one method over the other, and why?  Can you
	think of another approach that I've missed?
	Thanks for your time!
	Autumn A. Cuellar
	Bioengineering Institute
	The University of Auckland
	New Zealand
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