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DITA map files
Topic hierarchy
In DITA, the sequence and hierarchy of the topics to be published are defined in the ditamap through nested topicref elements.

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
- Purpose of ditamap files
  DITA map files are used for defining the topics of a publication, specifying the topic sequence, and controlling linking between topics.
- Topic manifest
  Any topics referenced anywhere in the ditamap will be processed into the output publication.
- Topic hierarchy
  In DITA, the sequence and hierarchy of the topics to be published are defined in the ditamap through nested topicref elements.
  - Designing a topic hierarchy
    A well-designed topic hierarchy will make the reader's task of finding information in a publication easier.
  - Heading levels and ditamaps
    The topic hierarchy in the ditamap is used to generate heading levels and styles in page layout outputs.
  - Controlling the top node (default topic)
    DITA publishing tools sometimes process the hierarchy of a ditamap slightly differently for different target output formats. A workaround can be used to achieve greater consistency between different outputs to avoid confusing readers.
  - Excluding topics from the output TOC
    When generating an output which includes a TOC, you may want to generate a topic from your ditamap but not have it appear in the output TOC. This is achieved through the toc and linking attributes of the topicref.
  - Creating a Glossary of Terms
    A Glossary of Terms is defined in a ditamap using either standard topicref elements to glossary entry topics, or using glossref elements (introduced in DITA 1.2).
- Relationship tables
  Relationship tables are used to store linking relationships between topics in a collection in the ditamap, rather than in individual topics. Linking relationships are defined in a table-like structure, with rows in the table determining which topics are linked to which.
- Linking relationships
  DITA encourages the linking relationships to be stored outside the topic content. Links can be generated from topic hierarchies, relationship tables, and related-links section links.
- Inheritance and cascades in ditamaps
  Properties in ditamaps sometimes cascade from parent elements to child elements. Some values in ditamaps also override the equivalent values in referenced topics.
- Embedded (or nested) ditamaps
  The technique of using embedded, or nested, ditamaps can make it easier to manage documents by separating complex collections of topics into a number of smaller, simpler collections.
- DITA map vocabulary
- The bookmap feature
  Bookmaps are a specialisation of the base DITA map information type. Like ditamaps, bookmaps are containers for structure and context metadata, and do not contain any content. Bookmaps are used to describe page layout publishing outputs such as books, articles, manuals and research papers. They contain information structures that are specific to linear publications, such as tables of figures, title pages, chapters, sections and parts.
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
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.

Topic hierarchy

In DITA, the sequence and hierarchy of the topics to be published are defined in the ditamap through nested topicref elements.

A topic-based document architecture relies on a device to bind the topics together into a structured output publication. A Help system is a good example of a topic-based document architecture. The binding device in Help systems is called the Table of Contents, or TOC. The TOC is used by the author to choose the topics that will be included in the publication, and the order in which they will be presented in navigation. In most Help systems, the TOC is also presented to the reader as an expandable and collapsible tree of links, which the reader can use to navigate through the document.

Example of a Table of Contents in a Help file — Figure 1. Example of a Table of Contents (from a Help file)

Being topic-based, DITA also needs a TOC-type device to bind collections of DITA topics together, and the ditamap is used for that purpose. The ditamap not only specifies what topics are to be included in the output, but specifies the sequence and hierarchy of the topics through nested topicref elements organised into a tree structure.

When DITA is transformed into a Help format, the ditamap is used to derive the appropriate TOC file. When DITA is transformed into a page layout format such as PDF, the ditamap is used to derive the Table of Contents and the heading styles in the output content.