13. Numbering the clauses and subclauses of a standard

13.1 Body clauses

The body of a standard is usually divided into several major clauses that are further divided into subclauses. The IEEE Standards system for numbering clauses uses Arabic numerals in sequence. A subclause should be numbered by adding a decimal point and number to the clause number (e.g., 5.1). Subclauses may be divided into further subclauses by adding a second decimal point and number (e.g., 5.1.1). Five numbers separated by decimal points is the maximum acceptable subdivision (e.g., 5.1.1.1.1). If necessary, the material should be reorganized to avoid subdivisions beyond this point. An exception to this numbering is allowed for amendments (see 20.2.1 for information on numbering in amendments and corrigenda).

Clauses and subclauses should be divided into further subclauses only when there is more than one subclause. For example, Clause 1 should not have a 1.1 unless there is also a 1.2.

All clause and subclause headings should consist of a number and a concise, meaningful, title. Text immediately follows the subclause title, but on a new line. Hanging paragraphs (i.e., unnumbered paragraphs following a main clause head or main subhead) should not be used since reference to the text would be ambiguous. It may be necessary to include a subhead with the title “General” to avoid instances of hanging paragraphs, as shown in Figure 1.

Figure 1Hanging paragraphs

The term Clause should be used when referring to major clause headings (e.g., “see Clause 5”) or at the beginning of a sentence. All other cross-references should be made by simply referring to the number (e.g., “see 5.1” not “see subclause 5.1”).

Standards are not published with line numbers (although numbers should be included in balloted drafts). Therefore, the working group should use only clause or subclause numbers in cross-references.

13.2 Numbering annexes

Consecutive capital letters and a title should be used to identify each annex. Text should be organized and numbered as described in 12.1, with the following exception: clause and subclause numbers should be prefaced with the identifying letter of the annex, followed by a period (see the example annex in Annex B). For standards containing only one annex, the letter A should appear in its title and should preface the clause and subclause numbers in the text. Figures and tables included in annexes should also carry the identifying letter of the annex in which they appear, followed by a period. For example, the first figure in Annex B should be identified as Figure B.1.

13.3 Lists

Lists in a subclause may be ordered or unordered. An ordered list of items within a subclause should be presented in outline form, with items lettered a), b), c), etc. If a subdivision of the items is necessary, 1), 2), 3); i), ii), iii); dashed subdivision items, etc., should be used to form a tiered list. Only one occurrence of any level of an ordered list may be presented in any subclause to avoid confusing cross-references [e.g., it is OK to have an a) level list followed by a 1) level list, etc., but there should not be more than one a) level list in the same clause or subclause]. As an alternate solution, authors may want to consider adding an additional subclause. Dashed lists can also be used instead of an ordered list if the list consists of short, unordered items. Annex B contains some examples of dashed lists. Closing punctuation should be omitted for phrases. Punctuation should be used for sentences. Lists shall be preceded by an introductory sentence explaining the relevance of the list. Figure 2 provides examples of the different levels in an ordered list.

Figure 2Example of a tiered list