How do you chose what to make #PCDATA and what to make an attribute?  Here's a rule: If it is data meant to be displayed or processed by the application, use PCDATA.  Only use tags for meta-data (data about the data).  Here's an example: Suppose you have some text to be displayed by an application.  If the user clicks on the text, you want the application to either make a noise or not.  Do it like this:

  <!DOCTYPE text
	[
	<!ELEMENT text #PCDATA>
	<!ATTRIBUTE text beep (yes | no) #REQUIRED>
	]
  >

  <text beep="yes">
	Here is the text to be displayed.  Whether the text beeps or
	not is NOT displayed -- that's why it's an attribute.
  </text>

References:

	* http://www.oasis-open.org/cover/elementsAndAttrs.html
	* http://java.sun.com/xml/docs/tutorial/overview/4_design.html

This page might be more accurately titled XmlPcDataVsXmlCdata
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That guideline works fine if the xml is document based. More and more, xml is being used as a data structure. Our rule is that basic data types and typecodes are attributes, objects map map to elements. Elements that define relationships wrap subelements. IOW,

        <facility unLocCode='us.fou' facilityId='cfs12'>
                <facilityOperator>
                        <party code='party2.com'/>
                </facilityOperator>
        </facility>

--JackBolles

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CategoryXml CategoryPattern CategoryComparisons XmlPattern ExtensibleMarkupLanguage