A topic type is a named collection of topic attributes: what window the Help topic appears in, how it's accessed, whether it gets a map number, where the heading paragraph appears, or if it appears at all. Topics are mapped to topic types by the style of their headings. The use of topic types streamlines the customizing process for the Help author, while helping maintain consistency. Adding a topic type can be achieved by right-clicking anywhere in the topic type list pane on the right side of the project editor.
For more information, see Using Topic Types.