<rng:element name="leaf">
 <rng:ref name="att.global.attributes"/>
 <rng:optional>
  <rng:attribute name="value">
   <rng:ref name="data.pointer"/>
  </rng:attribute>
 </rng:optional>
 <rng:optional>
  <rng:attribute name="parent">
   <rng:ref name="data.pointer"/>
  </rng:attribute>
 </rng:optional>
 <rng:optional>
  <rng:attribute name="follow">
   <rng:ref name="data.pointer"/>
  </rng:attribute>
 </rng:optional>
 <rng:optional>
  <rng:ref name="label"/>
 </rng:optional>
</rng:element>
element leaf
{
   att.global.attributes,
   attribute value { data.pointer }?,
   attribute parent { data.pointer }?,
   attribute follow { data.pointer }?,
   label?
}