An empty element

Note: all element rules may have a label. If omitted, it has the same value as the role

<elementRule role="name" label="name2">
   <empty/>
</elementRule>

<elementRule role="name" type="datatype"/>

Element with constraints on content

<elementRule role="name" type="datatype">
   <constraint value="constraint-value"/>
</elementRule>

<elementRule role="age" type="integer">
   <minInclusive value="18"/>
   <maxInclusive value="65"/>
</elementRule>

<elementRule role="name">
   <ref label="sub-element/>
</elementRule>

Element with sub-elements that must occur in a particular order

The occurs= attribute can have one of the following values:
  *   occurs zero or more times
  +   occurs one or more times
  ?   occurs zero or one times

<elementRule role="name">
   <sequence occurs="n">
      <ref label="sub-element1" occurs="n"/>
      <ref label="sub-element2" occurs="n"/>
   </sequence>
</elementRule>

<elementRule role="name">
   <choice occurs="n">
      <ref label="sub-element1" occurs="n"/>
      <ref label="sub-element2" occurs="n"/>
   </choice>
</elementRule>

Mixed content element (element can contain text that is not within any of the sub-elements)

The <mixed> element may enclose a <sequence> or <choice> as above.

<elementRule role="name">
   <mixed>
      <ref label="sub-element"/>
   </mixed>
</elementRule>

A content model for re-use by other elements:

Hedge rules may refer to other hedge rules, but may not have mixed content or data types.

<hedgeRule label="hedge-rule-label">
   <!-- content model as in elementRule -->
</hedgeRule>

Reference to a <hedgeRule>

You may intersperse <ref> and <hedgeRef> as required when defining an element's content.

<elementRule role="name">
   <hedgeRef label="hedge-rule-label"/>
</elementRule>

A tag with no attributes

All tags may have a role, which, if omitted, is given the same value as the label

<tag label="name" role="tag-role"/>

A tag with attributes

You may specify that an attribute is required, or that it has a particular data type, or both.

<tag label="name">
   <attribute name="attr-name-1"/>
   <attribute name="attr-name-2" required="true"/>
   <attribute name="attr-name-3" type="datatype"/>
   <attribute name="attr-name-4"
      required="true"
      type="datatype"/>
</tag>

Constraint on an attribute

<tag label="name">
   <attribute name="attr-name" type="datatype">
      <constraint value="constraint-value"/>
   </attribute>
</tag>

<tag label="water">
   <attribute name="temp" type="decimal">
      <minInclusive value="0"/>
      <maxInclusive value="100"/>
   </attribute>
</tag>

A set of attributes for re-use by other tags:

<attPool role="pool-label">
   <!-- list of attributes as in tag-->
</attPool>

Reference to an <attPool>

You may intersperse <ref> and <attribute> as required when defining a tag's attributes.

<tag label="name">
   <ref role="pool-label"/>
</tag>