In this chapter, the headings in the section Paragraphing, beginning on p. 548, provide a good example of a system of headings that can readily be outlined:
Paragraphing
Paragraph cues.
Topic sentence strategies.
Announcing the Topic
Making a Transition
Positioning the Topic Sentence
To learn more about distinguishing headings from surrounding text and about setting up systems of headings, see p. 644 in Chapter 21, Designing Documents.
Notice that in this example, the heading system has three levels. The first-level heading sits on its own line and is set in a large, red font; this heading stands out most visibly among the others. (It is one of five such headings in this chapter.) The second-level heading also sits on its own line but is set in a smaller font (and uses black type). The first of these second-level headings has no subheadings beneath it, while the second has three. These third-level headings, in black, do not sit on their own lines but run into the paragraph they introduce, as you can see if you turn back to pp. 549–51.
All of these headings follow a parallel grammatical structure: “-ing” nouns at the first level; nouns at the second level (“cues” and “strategies”); and “-ing” nouns at the third level.