P5: Guidelines for Electronic Text Encoding and Interchange

<rng:element name="usg">
 <rng:ref name="att.global.attributes"/>
 <rng:ref name="att.lexicographic.attributes"/>
 <rng:optional>
  <rng:attribute name="type">
   <rng:ref name="data.enumerated"/>
  </rng:attribute>
 </rng:optional>
 <rng:ref name="macro.paraContent"/>
</rng:element>

element usg
{
   att.global.attributes,
   att.lexicographic.attributes,
   attribute type { data.enumerated }?,
   macro.paraContent
}