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DITA map files
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.

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.
- 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.

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.

The topicref elements in a ditamap usually reference a topic. However, they can also reference ditamaps, which opens up the opportunity for having embedded (or nested) maps.

A reference to a ditamap differs from a reference to a topic in having a format attribute of ditamap. The syntax of a reference to a ditamap is:

<topicref 
  format="ditamap"
   href="engine/ej25.ditamap"
   navtitle="2.5 Litre Engine">
</topicref>

Figure 1 illustrates how ditamaps (such as the Storing Data and Widget Specifications ditamaps) can be nested within another ditamap (in this case, the Widget User Guide). Nesting can continue down to many levels deep. And ditamaps can be nested within many other ditamaps.

Diagram showing principle of re-used, embedded (or nested) ditamaps — Figure 1. Re-used, embedded (or nested) ditamaps

Nesting ditamaps is a useful tool in permitting content re-use and authoring efficiency.

The term mapref is sometimes used as shorthand for a topicref with a format attribute of ditamap. Until DITA 1.2, there was no DITA element of mapref, but 1.2 introduced a mapref as a convenience element identical in functionality to topicref with a format attribute of ditamap.