P5: Guidelines for Electronic Text Encoding and Interchange

<rng:element name="constitution">
 <rng:ref name="att.global.attributes"/>
 <rng:optional>
  <rng:attribute name="type" defaultValue="single">
   <rng:choice>
    <rng:value>single</rng:value>
    <rng:value>composite</rng:value>
    <rng:value>frags</rng:value>
    <rng:value>unknown</rng:value>
   </rng:choice>
  </rng:attribute>
 </rng:optional>
 <rng:ref name="macro.phraseSeq.limited"/>
</rng:element>

element constitution
{
   att.global.attributes,
   attribute type { "single" | "composite" | "frags" | "unknown" }?,
   macro.phraseSeq.limited
}