In some papers the chapters or their equivalents are divided into sections, which may in turn be divided into subsections, and these into sub- subsections, and so on. Such divisions are customarily given titles, called subheadings, which are designated respectively first-, second-, and third-level subheadings and differentiated from one another by typing style. The style of subheading with the greatest attention value should be given to the principal, or first-level, subdivision. On a type written page centered headings have greater attention value than side headings, and underlined headings, centered or side, have greater attention value than those not underlined. A plan for the display of five levels of subheadings in a typed paper follows:
First-level, centered heading, underlined:
Jesus and Paul
Fourth-level, side heading, not underlined:
The Gospel as initiated
Fifth-level, heading run into (at the beginning of) a paragraph and underlined:
The gospel legalized in the Church. The gospel that was offered by the early Christians to the pagans was made available through the Church.
Note that first- and second-level subheadings are typed in capital and small letters, and that lower-level subheadings capitalize only the first word, proper nuns, and proper adjectives.
If fewer than five levels are required, they may be selected in any suitable descending order, as indicated above. (For spacing subheadings see pars. 13:24- 25.)
All subheadings begin on the third line below text. if two or more subheadings appear together, a double space should be left between them, and a double space left also between the subheading and the text following.
Turabian, Kate L. A Manual for Writers of Term Papers, Theses and Dissertations. 4th ed. Chicago: U. Chicago Pr., 1973. 7-8, 195-196.