`<ditavalref>`

The <ditavalref> element references a DITAVAL document that specifies filter conditions that can be used to process a map or map branch. Other DITAVAL-reference domain elements can be used to imply multiple copies of the map branch that contains them and so apply a different set of conditions to each copy.

When a <ditavalref> element is included in a map, the conditions in the referenced DITAVAL document are used to filter the elements in the branch. The branch includes the parent element that contains the <ditavalref> element, any child elements, and all resources that are referenced by the parent element or its children. While there is no technical restriction that forces <ditavalref> to appear before peer topic references, placing them first is considered a best practice and all examples in the specification will use this convention.

In the simple case, a map can use <ditavalref> as follows:

<map>
  <topicref href="sampleBranch.dita" audience="admin">
    <topicmeta>
      <navtitle>Navigation title for branch</navtitle>
    </topicmeta>
    <ditavalref href="conditions.ditaval"/>
    <topicref href="insideBranch.dita" platform="win linux mac"/>
  </topicref>
  <!-- Other branches not affected by conditions.ditaval -->
</map>

The filtering conditions specified in the conditions.ditaval file apply to the following:

The <topicref> element that references sampleBranch.dita and all child elements: <topicmeta>, <navtitle>, and <topicref> elements
The sampleBranch.dita topic
The insideBranch.dita topic

When more than one <ditavalref> element is specified in the same branch at the same level, the effective result is one copy of the branch for each <ditavalref> element. If the example above contains a reference to otherConditions.ditaval as a peer to the existing <ditavalref> element, the rendered version of this map would reflect two copies of "Sample branch", each reflecting the conditions that are specified in the corresponding DITAVAL document. One copy is created using the conditions in conditions.ditaval, while the other copy uses the conditions from otherConditions.ditaval. Map authors can use specific elements from the DITAVAL reference domain to indicate how resources are renamed, or processors can recover from naming collisions by using an alternate naming scheme. See Limitations below for more information.

If DITAVAL conditions are specified at multiple levels within a single branch, "exclude" conditions that are specified at a higher level take precedence. In the following branch, assume alternate rules are specified for the condition audience="novice", with the value set to "exclude" in highLevel.ditaval and "include" in lowLevel.ditaval. In that case, the "exclude" condition specified in highLevel.ditaval takes precedence and so applies to the entire branch. This is true regardless of how the "exclude" condition is specified within highLevel.ditaval. That is, there might be a specific rule for audience="novice"; alternatively, the @audience attribute might be set to "exclude" by default, with no specific condition specified for the value audience="novice".

<topicref href="ancestor.dita">
  <ditavalref href="highLevel.ditaval"/>
  <topicref href="descendent.dita">
    <ditavalref href="lowLevel.ditaval"/>
    <!-- Other topicrefs -->
  </topicref>
</topicref>

If a <ditavalref> element is used that does not specify the @href attribute, the element is still processed but no additional filtering is applied. This can be used to create an unfiltered copy of a map branch alongside other filtered copies; other aspects of the <ditavalref> (such as any specified key scope or modified resource name) will still be applied to the branch.

Limitations

The following limitations apply when using the <ditavalref> element; these limitations cannot be enforced in a DTD or other XML grammar files.

When the use of the <ditavalref> element results in multiple copies of a branch, resource names within that branch can be controlled with sub-elements of the effective <ditavalref>. For situations where resource names are relevant, it is an error condition for multiple <ditavalref> elements to result in conflicting resource names for different content. For example, the following map fragment would result in two distinct copies of the c.dita topic with the same file name:

<topicref href="c.dita">
  <ditavalref href="one.ditaval"/>
  <ditavalref href="two.ditaval"/>
</topicref>

Processors MAY recover by using an alternate naming scheme for the conflicting copies.

Content models

See appendix for information about this element in OASIS document type shells.

Inheritance

+ map/topicref ditavalref-d/ditavalref

Example

See Examples of branch filtering for several examples of the <ditavalref> element.

Attributes

The following attributes are available on this element: Universal attribute group (except for @conkeyref, which is removed for all elements in this domain) and the attributes defined below.

@href: Provides a reference to a DITAVAL document. If the @href attribute is unspecified, this <ditavalref> will not result in any new filtering behavior, but other aspects of the element are still evaluated. See The href attribute for general information on the format and processing implications of the @href attribute.
@format: Format of the target document, which MUST be a DITAVAL document. The default value for this element is "ditaval". See The format attribute for more information.
@processing-role: The processing role defaults to "resource-only" for DITAVAL documents, which are only used for processing and do not contain content. There is no other valid value for this attribute on this element.