<constraint>

<constraint> (constraint rules) the formal rules of a constraint
組件tagdocs — 22 Documentation Elements
屬性att.global (@xml:id, @n, @xml:lang, @rend, @rendition, @xml:base, @xml:space) (att.global.linking (@corresp, @synch, @sameAs, @copyOf, @next, @prev, @exclude, @select)) (att.global.analytic (@ana)) (att.global.facs (@facs))
屬於
可包含在於
tagdocs: constraintSpec
可包含ANY
宣告

<rng:element name="constraint">
 <rng:ref name="att.global.attributes"/>
 <rng:ref name="att.global.linking.attributes"/>
 <rng:ref name="att.global.analytic.attributes"/>
 <rng:ref name="att.global.facs.attributes"/>
 <rng:choice>
  <rng:text/>
  <rng:ref name="macro.anyXML"/>
 </rng:choice>
</rng:element>
element constraint
{
   att.global.attributes,
   att.global.linking.attributes,
   att.global.analytic.attributes,
   att.global.facs.attributes,
   ( text | macro.anyXML )
}
例子
<constraintSpec ident="local" scheme="private">
 <constraint>
   (output = (ident(title) ident(author) "You must supply a title or an author"))
 </constraint>
</constraintSpec>