Addition of new units between existing units

(a) If it becomes necessary to introduce a new chapter or section between existing chapters or sections the new chapter or section shall be designated by the addition of a letter suffix to the preceding chapter or section number. Thus, a chapter introduced between Chapters 31 and 32 would be numbered Chapter 31a, and a section introduced between § 3.11 and § 3.12 would be numbered § 3.11a. When a number of the chapter or section numbers have been introduced, the entire portion of the title or chapter shall be revised and renumbered. (b) If it becomes necessary to introduce a subsection between existing subsections, and revision of the entire section is not desirable, the new subsection shall be designated by the addition of a hyphen and Arabic numeral to the letter designating the preceding subsection.

Thus, a subsection introduced between subsections (a) and (b) would be numbered as subsection (a-1). (c) If it becomes necessary to introduce a unit smaller than a subsection between existing units, the entire subsection shall be revised.