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Content re-use
Re-use practices
Nested content references
Content references can be nested inside other content references.

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
  - Writing for re-use
    You should embrace a style or method of writing that produces content suitable for re-use. This method includes an aim to minimise context.
  - Re-use guidelines
    Re-use guidelines can help simplify the practice of writing for re-use.
  - Valid referencing elements
    When using a conref in a topic to transclude text from another topic, the referencing element must be valid DITA XML.
  - The -dita-use-conref-target attribute value
    A special attribute value of -dita-use-conref-target can be used to force the attribute value of the source of a conref to be used in the referencing element.
  - Re-using content from different elements
    When re-using content through the conref feature, the referenced element type must match the referencing element type.
  - Nested content references
    Content references can be nested inside other content references.
- Variables
- 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.

Nested content references

Content references can be nested inside other content references.

Nested conrefs are content references within other content references. For example, a company name variable might be transcluded into a product name variable.

For example, the company name Supara might be transcluded by itself, or within the full product name Supara Impress XRW, which itself includes the product trademark.

Schematic diagram showing a phrase and a tm element nested inside a phrase element — Figure 1. Nested conref principles

The DITA code for such a nested conref might be:

<p>The <ph conref="co.dita#corpnames/var_xrw" /> was released in 1990.</p>

where the var_xrw ph element in co.dita is:

<ph id="var_xrw">
  <ph conref="#corpnames/co"/> <tm conref="#corpnames/impxrw" tm="-dita-use-conref-target"/>
</ph>

and the co and impxrw elements are:

<ph id="co">Supara</ph>
...
<tm id="impxrw" tmtype="reg" tmowner="FJ Heavy Industries">Impress XRW</tm>

DITA 1.2 introduced the text element. Use this element in preference to the ph element for re-using text snippets.