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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.
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.
Glossary entry
The glossentry specialised information type was introduced to improve the glossary and terminology management.

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.
  - Concept
    The concept topic is one of the three base DITA information types.
  - Task
    The task topic is one of the three base DITA information types.
  - Reference
    The reference topic is one of the three base DITA information types.
  - Glossary entry
    The glossentry specialised information type was introduced to improve the glossary and terminology management.
  - Composite (ditabase)
    The composite or ditabase topic is a now obsolete tool for collecting multiple topics and nesting them within a single topic file.
  - Topic (proto information type)
    The topic information type is the ancestor of all DITA information types, and is used mainly as the basis for specialising new information types.
  - Identifying the information type
    Concept, task and reference topics contain different types of content. Concept topics contain explanations, task topics contain procedural steps, and reference topics contain tabular look-up information.
- 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.
- 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.

Glossary entry

The glossentry specialised information type was introduced to improve the glossary and terminology management.

The glossary entry (glossentry) information type is part of the DITA standard, but is not widely seen as one of the base DITA information types. Technically, it is a specialisation of the base concept information type.

Schematic diagram showing base and specialised information types in DITA — Figure 1. Base and specialised information types

The structure of glossentry is quite simple. There are two main block elements: glossterm and glossdef. The glossterm element (a specialised title) contains the name of the term, while the glossdef element (a specialised abstract) contains the definition of the term.

Just one term should be defined in one glossary entry topic.

A document's glossary of terms is created by grouping glossary entry topics in the ditamap. Except for small documents, using a separate ditamap for the glossary, and then embedding the glossary ditamap in the main map for the collection, is the architecture most easy to manage.

The linking of a term occurring in-line in a normal content topic to its relevant glossentry definition is a matter of associating the term (semantically identified in a term element) with the key reference (keyref) of the glossary topic, and relying on the publishing process to create the link.

The root element of a glossary entry topic is glossentry.