The capital letters (A, B, C, etc.) mark the main divisions of the subject.
The Roman capital numerals (I, II, III, IV, etc.) mark the subdivision of A, B, C, etc.
The Arabic figures (1, 2, 3, 4, etc.) mark the subdivision of I, II, III, etc.
The small or lower-case letters (a, b, c, etc.) mark the subdivision of 1, 2, 3, etc. The italic letters are generally used.
If there is only a single enumeration, the Arabic figures (1, 2, 3, etc.) are used.
If there are one enumeration and one subdivision, the Arabic figures and the lower-case letters are used.
If one or more of the first divisions are subdivided, and one or more of such subdivisions are subdivided, the Roman numerals, the Arabic figures, and the lower-case letters are used.
The enumerating letters (A, B, etc.) of the first, or main, divisions are indented the space of the usual paragraph; the subdivisions of the first divisions are so far indented that their enumerating letters or figures are in alignment with the first letter of the first word under the division above. This mode of indention is continued with the next subdivisions, thus putting the enumerating letters or figures of the respective divisions or subdivisions in perpendicular alignment. This mode of enumeration and indention can be illustrated diagrammatically:
89.
A. The capital letters (A, B, C, etc.) will mark the main divisions of the subject.
I. The Roman numerals (I, II, III, etc.) will mark the subdivisions of A, B, C, etc.
1. The Arabic figures (1, 2, 3, etc.) will mark the subdivisions of I, II, III, etc.
a. The italic lower-case letters (a, b, c, etc.) will mark the subdivisions of 1, 2, 3, etc.
B. Here follows the second main division, its enumerating letter (B) being in perpendicular alignment with “A,” above.