# `<topicset>`

The `<topicset>` element defines a complete unit of content that can be reused in other DITA maps or other `<topicset>` elements. Unlike the base `<topicref>` element, the `<topicset>` is explicitly intended to define a set of topics that are often or always used as a unit; it can be especially useful for task composition in which larger tasks are composed of smaller tasks. The `@id` attribute on a `<topicset>` is required, which ensures that the complete unit is available for reuse in other contexts.

Category: Map group elements