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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.
Specialised information types
Specialised information types provide a topic architecture that closely matches the structure of your content.
Types of specialisation
Structural specialisation is used to design completely new information types. Domain specialisation is used to modify the design of semantic elements within an information type.

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.
- Content models and information types
  A content model is a framework that represents the structure of the information to be stored. In DITA, a content model is implemented as an information type, or topic type.
- Information types
  A fundamental principle of DITA is information typing, which categorises information according to the nature of the content. The three base DITA information types are concept, task and reference.
- What is a topic?
  A topic in DITA is an independent chunk of information covering a single idea or task, authored as a unit, and stored in its own file. Topics are categorised by information type. DITA's topic-based architecture enables the same topic to be used in different publications.
- Working with topics
- Specialised information types
  Specialised information types provide a topic architecture that closely matches the structure of your content.
  - Types of specialisation
    Structural specialisation is used to design completely new information types. Domain specialisation is used to modify the design of semantic elements within an information type.
  - Official specialisations
    Some specialised information types have been developed by the same standards body that is responsible for the DITA standard itself.
  - To specialise or not to specialise
    Specialisation has pros and cons. It adds technical complexity, but can provide better and more appropriate information structures. Specialisation should be carefully planned.
  - Limits on specialisation
    DITA specialisations must conform with immutable rules contained within the DITA specification.
- Topic exemplars
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
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.

Types of specialisation

Structural specialisation is used to design completely new information types. Domain specialisation is used to modify the design of semantic elements within an information type.

There are two types of specialisation:

structural specialisation (topic or map level), and
domain specialisation (element level).

Structural specialisation is used to design completely new information types, such as an architecture to suit Java API documentation.

Schematic showing examples of specialised information types evolved from the base information types — Figure 1. Examples of specialised information types

Domain specialisation is used to modify the design of the semantic elements and attributes within an information type, such as creating a new element named partnumber.

Sometimes, configuration is confused with specialisation. Configuration is a technique where the author or organisation chooses not to use all the DITA elements and topic types. Configuration restricts, but does not extend. Specialisation defines new elements and information types.