P5: Linee guida per la codifica e l'interscambio del testo elettronico

<rng:element name="purpose">
<rng:ref name="att.global.attributes"/>
<rng:optional>
 <rng:attribute name="type">
  <rng:choice>
   <rng:value>persuade</rng:value>
   <rng:value>express</rng:value>
   <rng:value>inform</rng:value>
   <rng:value>entertain</rng:value>
   <rng:data type="Name"/>
  </rng:choice>
 </rng:attribute>
</rng:optional>
<rng:optional>
 <rng:attribute name="degree">
  <rng:ref name="data.certainty"/>
 </rng:attribute>
</rng:optional>
<rng:ref name="macro.phraseSeq.limited"/>
</rng:element>

element purpose
{
   att.global.attributes,
   attribute type
   {
      "persuade" | "express" | "inform" | "entertain" | xsd:Name
   }?,
   attribute degree { data.certainty }?,
   macro.phraseSeq.limited
}