P5: Guidelines for Electronic Text Encoding and Interchange

<rng:element name="tech">
 <rng:ref name="att.global.attributes"/>
 <rng:optional>
  <rng:attribute name="type">
   <rng:choice>
    <rng:value>light</rng:value>
    <rng:value>sound</rng:value>
    <rng:value>prop</rng:value>
    <rng:value>block</rng:value>
   </rng:choice>
  </rng:attribute>
 </rng:optional>
 <rng:optional>
  <rng:attribute name="perf">
   <rng:ref name="data.enumerated"/>
  </rng:attribute>
 </rng:optional>
 <rng:ref name="macro.paraContent"/>
</rng:element>

element tech
{
   att.global.attributes,
   attribute type { "light" | "sound" | "prop" | "block" }?,
   attribute perf { data.enumerated }?,
   macro.paraContent
}