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Content re-use
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Variables using indirection
The keyword element can be used as a container for variable words and phrases, when used in conjunction with the keydef element in the ditamap. Rather than enter the value of the keyword directly into the element, you can indirectly reference it through a key.

Introduction
Information types and topics
Topics are the building blocks of modular documents, and organising topics by semantic information types is one of the architectural features of DITA.
DITA map files
Syntax and mark-up
Language and punctuation
Graphics and figures
Cross-referencing
Cross-references are a means of binding individual topics into a coherent and navigable document.
Content re-use
- Content re-use definition
  Content re-use is a means of improving efficiency by eliminating repetition of phrases, blocks of text, topics, and even collections of topics.
- Re-use and the DITA Maturity Model
  Content re-use is one of the features that you should adopt early in your move from style-based authoring to structured authoring with DITA.
- The content reference (conref) attribute
  The conref feature allows DITA content to be used in any number of different places in a collection. The conref attribute in a referencing topic specifies the source topic and the element within that topic to re-use.
- Re-use practices
- Variables
  - Variables using conref and filtering
    Single-source publishing relies heavily on the concept of variables. While DITA does not have a specifically named variables feature, it does readily support variables functionality.
  - Variables using indirection
    The keyword element can be used as a container for variable words and phrases, when used in conjunction with the keydef element in the ditamap. Rather than enter the value of the keyword directly into the element, you can indirectly reference it through a key.
  - Using internal entities for variables
    Internal entities are an XML feature for creating typing shortcuts. They should be avoided in DITA authoring.
- Organising re-use topics and elements
- Embedded topics and ditamaps
  The ditamap is a powerful tool for re-using topics in different output publications. Topics can also be re-used using ditabase topics, but you should avoid this technique.
- Advanced conref principles
Metadata, conditional processing, and indexing
The DITA documentation process
DITA authoring concepts
Moving from style-based authoring to a structured authoring methodology such as DITA requires a radically different approach to writing.

Variables using indirection

The keyword element can be used as a container for variable words and phrases, when used in conjunction with the keydef element in the ditamap. Rather than enter the value of the keyword directly into the element, you can indirectly reference it through a key.

The keyref feature introduced in DITA 1.2 allows re-used terms or phrases that often vary according to output publication to be managed more easily. You can collect such variable terms into a keydef section in the ditamap, and then use the keyword and its keyref attribute to re-use them. You must also nominate a fallback value, in case the relevant key is not defined in any ditamap in which the topic is referenced.

Because the content model of the keyword element in a ditamap is different to that in a topic, you have to contain the ditamap keyword element within topicmeta and keywords elements.

As a simple example, a generic car component topic can include the name of the specific car in whose manual the topic appears. A sentence in the generic topic may be:

Your <keyword keyref="car_name">car<keyword> has high intensity discharge headlamps.

If that topic is included in a ditamap with a key defined as:

<keydef keys="car_name">
  <topicmeta><keywords><keyword>Liberty</keyword></keywords></topicmeta>
</keydef>

the topic will be rendered as:

Your Liberty has high intensity discharge headlamps.

In this example, if the ditamap didn't have a definition for the car_name key, the word car, which is the value of the keyword element in the topic, would be used in the output.

Note:

You may find it easier to manage keys in the ditamap if you use a separate, nested ditamap to contain the keys only.