P5: Guidelines for Electronic Text Encoding and Interchange

<rng:element name="charDecl">
<rng:ref name="att.global.attributes"/>
<rng:group>
 <rng:optional>
  <rng:ref name="desc"/>
 </rng:optional>
 <rng:oneOrMore>
  <rng:choice>
   <rng:ref name="char"/>
   <rng:ref name="glyph"/>
  </rng:choice>
 </rng:oneOrMore>
</rng:group>
</rng:element>

element charDecl { att.global.attributes, ( desc?, ( char | glyph )+ ) }