SubheadingsSubheadings enable your readers to find detailed information quickly. They also give the reader an idea of how deeply a topic is covered.
Subheadings provide more detail about the topic stated in the main entry. Effective subheadings represent distinct aspects of a topic. The following example, from Beyond Public Architecture: Strategies for Design Evaluations, includes the city with each subheading. Ideally, each subheading has only one or two page references:
Sometimes a topic, or main heading, can be divided into sub-classifications. For example, vehicles could be subdivided into “types of” vehicles such automobiles, trucks and buses. Similarly, a house could be subdivided into “parts of” the house such as walls, rooms, roof, plumbing, etc.
Sub-classifications of a main heading make poor subheadings because they do not tell the reader more “about” the topic. Ideally, a sub-classification should be raised to a main heading with a “See also” cross-reference from the original main topic. In the following example, from Concepts of Mass in Contemporary Physics and Philosophy, the main heading “general relativity” makes a “See also” cross-reference to two sub-classifications, “relativity, Einstein's theory of” and “special relativity”:
Market research has shown that comprehensive indexes improve book sales. And with customer documentation, finding the answer quickly will reduce the likelihood of an expensive customer support call.