HL7 use of xs:anyType extension

["Pete Cordell" <petexmldev@tech-know-ware.com>]

I've been looking at the HL7 schema and I see that a type is defined to be
an extension of an xs:anyType, as shown below...

 <xsd:complexType name="varies">
  <xsd:complexContent>
   <xsd:extension base="xsd:anyType"/>
  </xsd:complexContent>
 </xsd:complexType>

I've seen (incorrect) comments on the web that say this is an attempt to 
define an empty element.  Is this HL7's intent?  Or is it just an attempt to 
map the name 'varies' to xsd:anyType?

The above type is then used in the following situation...

  <xsd:complexType name="MFA.5.CONTENT">
    <xsd:complexContent>
      <xsd:extension base="varies">
        <xsd:attributeGroup ref="MFA.5.ATTRIBUTES"/>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>

What sorts of XML instances should this map to?  An empty element with 
attributes as defined in the attributeGroup?  Or, any number of attributes 
and element body content, that must also include the set of attributes 
defined in the attributeGroup?  i.e. is this some way of defining an 
extensible instance?

Thanks for any explanations.

Pete.
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Pete Cordell
Tech-Know-Ware Ltd
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