P5: Guidelines for Electronic Text Encoding and Interchange

<rng:element name="attList">
<rng:ref name="att.global.attributes"/>
<rng:optional>
 <rng:attribute name="org" a:defaultValue="group">
  <rng:choice>
   <rng:value>group</rng:value>
   <rng:value>choice</rng:value>
  </rng:choice>
 </rng:attribute>
</rng:optional>
<rng:oneOrMore>
 <rng:choice>
  <rng:ref name="attRef"/>
  <rng:ref name="attDef"/>
  <rng:ref name="attList"/>
 </rng:choice>
</rng:oneOrMore>
</rng:element>

element attList
{
   att.global.attributes,
   attribute org { "group" | "choice" }?,
   ( attRef | attDef | attList )+
}