P5: Guidelines for Electronic Text Encoding and Interchange

<rng:element name="shift">
<rng:ref name="att.global.attributes"/>
<rng:ref name="att.ascribed.attributes"/>
<rng:optional>
 <rng:attribute name="feature">
  <rng:choice>
   <rng:value>tempo</rng:value>
   <rng:value>loud</rng:value>
   <rng:value>pitch</rng:value>
   <rng:value>tension</rng:value>
   <rng:value>rhythm</rng:value>
   <rng:value>voice</rng:value>
  </rng:choice>
 </rng:attribute>
</rng:optional>
<rng:optional>
 <rng:attribute name="new" a:defaultValue="normal">
  <rng:ref name="data.enumerated"/>
 </rng:attribute>
</rng:optional>
<rng:empty/>
</rng:element>

element shift
{
   att.global.attributes,
   att.ascribed.attributes,
   attribute feature
   {
      "tempo" | "loud" | "pitch" | "tension" | "rhythm" | "voice"
   }?,
   attribute new { data.enumerated }?,
   empty
}