<enumerationdef>

An enumeration definition is a binding of an attribute to a set of controlled values. The set of controlled values can be limited to a specific element or it could be empty.

Usage information

An enumeration definition can accomplish the following goals:

Bind a set of controlled values to an attribute
When the <enumerationdef> element contains only an <attributedef> and a <subjectdef> element, the set of controlled values that are bound to the attribute apply to all elements. For example, when <enumerationdef> contains only <attributedef name="value"/>, the @value attribute is limited to the specified enumeration for all elements that can specify the @value attribute.
Limit a set of controlled values to a specific element and attribute pair
When the <enumerationdef> element contains an <attributedef>, a <subjectdef>, and an <elementdef> element, the enumeration applies to the specified attribute only on the specified element. The enumeration does not apply to the attribute on other elements.

For example, when the <enumerationdef> element contains both <attributedef name="type"/> and <elementdef name="note"/>, only the @type attribute on the <note> element is limited to the specified enumeration. The possible values for the @type attribute on other elements are not affected.

Specify the default value for an attribute or element and attribute pair
When the <enumerationdef> element contains a <defaultSubject> element, processors operate as if the value specified by the <defaultSubject> element is explicitly set in the DITA source and the XML grammar does not set a default value for the attribute.

For example, given the following <enumerationdef> element, if no value is set for the @audience attribute on <draft-comment> in the DITA source, processors operate as if the @audience attribute is explicitly set to spec-editors:

<subjectScheme>
  <!-- ... -->
  <enumerationdef>
    <elementdef name="draft-comment"/>
    <attributedef name="audience"/>
    <subjectdef keyref="values-audience-draft-comment"/>
    <defaultSubject keyref="spec-editors"/>
  </enumerationdef>
  <!-- ... -->
</subjectScheme>
Specify that an attribute is not valid.

When the <enumerationdef> element contains a @subjectdef element that does not reference a subject, no value is valid for the attribute.

For example, the following code sample specifies that no tokens are valid for the @props attribute:
<subjectScheme>
  <!-- ... -->
  <enumerationdef>
    <attributedef name="props"/>
    <subjectdef/>
  </enumerationdef>
  <!-- ... -->
</subjectScheme>

Specialization hierarchy

The <enumerationdef> element is specialized from <topicref>. It is defined in the subject scheme module.

Processing expectations

See Determining effective attribute values

Attributes

The following attributes are available on this element: ID and conref attributes, @base, @class, @outputclass, and @status.

Example

The following code sample contains three enumeration definitions:

<subjectScheme>
    
    <!-- DEFINE SETS OF CONTROLLED VALUES -->

    <!-- 1. Values for @audience on <draft-comment> -->
    <subjectdef keys="values-audience-draft-comment">
        <subjectdef keys="spec-editors"/>
        <subjectdef keys="tc-reviewers"/>
    </subjectdef>
    
    <!-- 2. Values for @otherprops -->
    <subjectdef keys="values-otherprops">
        <subjectdef keys="examples"/>
    </subjectdef>
    
    <!-- BINDS SETS OF CONTROLLED VALUES -->

    <!-- 1. Binding for @audience on <draft-comment> -->
    <enumerationdef>
        <elementdef name="draft-comment"/>
        <attributedef name="audience"/>
        <subjectdef keyref="values-audience-draft-comment"/>
        <defaultSubject keyref="spec-editors"/>
    </enumerationdef>
    
    <!-- 2. Binding for @otherprops -->
    <enumerationdef>
        <attributedef name="otherprops"/>
        <subjectdef keyref="values-otherprops"/>
    </enumerationdef>

    <!-- 3. Binding for @props -->
    <enumerationdef>
        <attributedef name="props"/>
        <subjectdef/>
    </enumerationdef>

</subjectScheme>
  1. The permissible values for the @audience attribute on the <draft-comment> element are restricted to the subject values-audience-draft-comment. This means that the only allowed values are spec-editors and tc-reviewers. If no value for @audience is specified for a <draft-comment> element in the DITA source, it is assumed to be set to spec-editors.
  2. The permissible values for @otherprops are restricted to the subject values-otherprops. This means that the only valid value for @otherprops is examples.
  3. The enumeration for the @props attribute contains a <subjectdef> element that does not reference a subject. That means that no values are valid for the @props attribute.