3.1.3.3.1 exportanchors

The <exportanchors> element is used to delay conref resolution within DITA documents. This allows you to process or display DITA content in a way that will resolve only some of the conref values in that content, while remaining values are left for later resolution. The element contains a list of IDs or keys that should not be resolved during the initial preparation of the content for display; those IDs and keys will be preserved after that preparation, as will the conref relationship itself.

The exportanchors element may be used within a topic prolog, in which case the defined IDs apply to IDs within that topic (excluding sub-topics). Alternatively it may be defined in the topicmeta in a map. In the second case the IDs apply to the single topic referenced by the current topicref element. If the topicref points to a file without referencing a specific topic, it is treated as a reference to the first or root topic. In order to define anchor ids for a topic that is not the first or root topic, a topicref must directly reference the desired sub-topic.

Note: When an element's ID is defined for delayed resolution, it must contain only the element ID, not the usual "topicid/elementid" syntax that is required for most other DITA references. The <anchorid> topic explains the format in detail.

One possible way to use this is with a system that renders DITA dynamically. A user may process information locally in a way that resolves conref for all static information, while delaying resolution for information that is subject to change. The exportanchors element is used to define conref values that are delayed.

Another potential use is when DITA is used as the source format for a publishing system that is able to render information dynamically. In this case some conref values may be resolved, while leaving pre-selected values to be resolved live in that publishing system.

Many publishing systems for which DITA is used as a source format do not have a way to dynamically resolve content references; those systems will not see any benefit from this element. When DITA is used for those systems, behaviors related to this element should be ignored.

Contains

Note: These models represent only the default document types distributed by OASIS. Actual content models will differ with each new document type.
Doctype Content model
map, bookmap, classifyMap, learningBookmap, learningMap (anchorid or anchorkey) (any number)

Contained by

Doctype Content model
map (base), map (technical content), classifyMap, learningMap metadata, topicmeta
bookmap, learningBookmap metadata, topicmeta, bookmeta

Inheritance

+ topic/keywords delay-d/exportanchors

Example

Figure 1. Use case 1: Runtime resolution of conref to an id, determined by original author
  1. Author 1 creates topics for information component A, which is a common component used by many products. The configuration task for component A is often reused in whole or in part, so the author assigns ids to each of the steps in the procedure and exports them. 
    <task id="configA">
  <title>ABC<title>
  <shortdesc>...</shortdesc>
  <prolog><metadata>
    <exportanchors>
      <anchorid id="step1"/>
      <anchorid id="step2"/>
      <anchorid id="step3"/>
    </exportanchors>
  </metadata></prolog>
  <taskbody>
    <steps>
      <step id="step1"><cmd>Do this</cmd></step>
      <step id="step2"><cmd>Do the other</cmd></step>
      <step id="step3"><cmd>And then finish</cmd></step>
    </steps>
  </taskbody>
</task>
  2. Author 2 is working on information component B, which has information component A as a prerequisite.
  3. Author 2 creates a configuration task that reuses two steps from the configuration task in information component A.
    <task id="configB">
  <title>..</title>
  <shortdesc>..</shortdesc>
  <taskbody>
    <steps>
      <step><cmd>Do the very first thing</cmd></step>
      <step conref="componentA/configA.dita#configA/step1"><cmd/></step>
      <step><cmd>Do the middle thing</cmd></step>
      <step conref="componentA/configA.dita#configA/step2"><cmd/></step>
    </steps>
  </taskbody>
</task>
  4. Author 2 builds the content for component B into a deliverable format that supports dynamic content resolution. As with traditional conref, the source for component A must be available during this process. Because the ids in configA are exported, the build process knows to preserve the reuse relationship rather than resolve it - so the conref to the steps becomes an equivalent reuse artifact in that deliverable format. This way the relationship to component A can be resolved at runtime, and pick up the user's version of component A, which may be more up-to-date than the one used by Author 2 when component B was built.
Figure 2. Use case 2: Runtime resolution to an id exported by the information builder
  1. Author 1 is creating content that will be packaged into multiple deliverable components. In one of those components, component A, the ids should be exported for runtime reuse by other components. In other components, the ids should not be exported because all reuse is local (for example, the output is a single infocenter, or a helpset that has only one component).
  2. When author 1 builds component A, the author uses a map that exports the ids, rather than exporting the ids from the topic prolog. 
    <map>
  <topicref href="componentA/configA.dita">
    <topicmeta>
      <exportanchors>
        <anchorid id="step1"/>
        <anchorid id="step2"/>
        <anchorid id="step3"/>
      </exportanchors>
    </topicmeta>
  </topicref>
</map>
  3. The rest of the use case is the same as previous - the conref is passed on to the runtime/display format to deal with, rather than being resolved during native DITA processing.
Figure 3. Delaying resolution for a topic

The ID on an <anchorid> element is first compared with the topic's id, and then with elements inside that topic. This results in the following situation.

<map>
  <topicref href="componentA/this.dita">
    <topicmeta>
      <exportanchors>
        <anchorid id="this"/>
        <anchorid id="that"/>
      </exportanchors>
    </topicmeta>
  </topicref>
</map>

<topic id="this">
  <title>This and that</title>
  <shortdesc>Oh, you know, this and that.</shortdesc>
  <body>
    <fig id="that"><p>more of that</p></fig>
  </body>
</topic>
  • The first ID to be exported is "this", which matches the topic id, so resolution of conref values that target the topic should be delayed.
  • The second value is "that", which matches a figure within the topic, so resolution of conref values that target the figure should be delayed.
  • Note that if the "this" is also used within the topic (which is legal from a DITA perspective), it will not be possible to export that id, because processors will match on the topic's id first.

Example

In this example, a set of information contains multiple components. Some references to component A use keys rather than a direct reference, so that conref can be redirected to a different component when component A is not installed. The keys may be exported, in addition to the IDs, so that some references become bound to the actual component while other references may be redirected.

<map>
  <topicref keys="componentAconfig commonconfig" 
            href="componentA/configA.dita#configA">
    <topicmeta>
      <exportanchors>
        <anchorkey keyref="commonconfig"/>
        <anchorid id="step1"/>
        <anchorid id="step2"/>
      </exportanchors>
    </topicmeta>
  </topicref>
</map>

The keys attributes declares two distinct keys that may be used to refer to this topic (componentAconfig and commonconfig). Only the second is preserved using anchorkey. A task topic from another component may reuse steps within this topic in a variety of ways.

<steps>
  <step conkeyref="componentAconfig/step1"><cmd/></step>
  <step conkeyref="componentAconfig/step1.5"><cmd/></step>
  <step conkeyref="commonconfig/step2"><cmd/></step>
  <step conkeyref="commonconfig/step2.5"><cmd/></step>
  <step><cmd>And that is the end of that</cmd>
</steps>

This allows the information assembler to resolve references that must be to componentA while deferring references that can be fulfilled by alternative component content.

Note: This example demonstrates why the anchorid element cannot reference an element with the usual topicid/elementid format. If the two anchorid elements in the example had been set to config/step1 and config/step2, then they would only ever apply in a topic with id="config". It would not be possible to redirect the key to another topic, but still preserve conref behaviors as desired.
Note: Although it is not specifically called out in this example, it is possible to delay conref resolution for an entire topic using the key. If conkeyref on a task topic element is set to "componentAconfig", which is not delayed, the conref will be evaluated as usual. However, if conkeyref on the task is set to "commonconfig", which is delayed, resolution of conref on that element should be delayed by a processor.

Attributes

Name Description Data Type Default Value Required?
univ-atts attribute group (includes select-atts, id-atts, and localization-atts groups) A set of related attributes, described in univ-atts attribute group      
global-atts attribute group (xtrf, xtrc) A set of related attributes, described in global-atts attribute group      
class A common attribute described in Other common DITA attributes      
Parent topic: 3.1.3.3 Delayed conref resolution elements
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OASIS DITA Version 1.2 -- OASIS Standard, 1 December 2010
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