Maintains the specifications for XML itself.
    
      - XML 1.0
- Namespaces in XML 1.0
- XML Base
- XML Information Set
<p:activity xmlns:p='http://www.w3.org/Consortium'
          xml:base='http://www.w3.org/'>
  <p:name>XML Activity</p:name>
  <p:location uri='XML/'/>
</p:activity>