a definition of topic

["Bruce Nevin (bnevin)" <bnevin@cisco.com>]

Here's my first offering of a definition:

Topic
A body of content that develops a single subject in a self-contained way. A series of topics may develop a complex subject, but it develops one aspect of that subject at a time, each of which is a topic. A topic is formally characterized by limited vocabulary pertaining to its subject and by a unity of voice and style. Typically, the subject is identified in a title and briefly delineated in a first paragraph, although these characteristics may not be universal to all topic types.

Here is a definition from the spec (2.1.1.3 Basic concepts, 2.1.2.1.1 The topic as the basic unit of information):

In DITA, a topic is the basic unit of authoring and reuse. All DITA topics have the same basic structure: a title and, optionally, a body of content. Topics can be generic or more specialized; specialized topics represent more specific information types or semantic roles, for example, <concept>, <task>, <reference>, or <learningContent>.

 

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And farther along in 2.1.2.1.1:

Classically, a DITA topic is a titled unit of information that can be understood in isolation and used in multiple contexts. It should be short enough to address a single subject or answer a single question but long enough to make sense on its own and be authored as a self-contained unit. However, DITA topics also can be less self-contained units of information, such as topics that contain only titles and short descriptions and serve primarily to organize subtopics or links or topics that are designed to be nested for the purposes of information management, authoring convenience, or interchange.