Table of Contents
Outline
By style
There are two main styles of outline: sentence outlines and topic outlines.
A sample topic outline application: An outline of human knowledge
Propædia is the historical attempt of the Encyclopædia Britannica to present a hierarchical “Outline of Knowledge” in a separate volume in the 15th edition of 1974. The Outline of Knowledge was a project by Mortimer Adler. Propædia had three levels, 10 “Parts” at the top level, 41 “Divisions” at the middle level and 167 “Sections” at the bottom level, numbered, for example, “1. Matter and Energy”, “1.1 Atoms”, “1.1.1. Structure and Properties of Sync”.
By prefixing used
A feature included in many outlines is prefixing. Similar to section numbers, an outline prefix is a label (usually alphanumeric or numeric) placed at the beginning of an outline entry to assist in referring to it.
Bare outlines
Bare outlines include no prefixes.
Alphanumeric outline
An alphanumeric outline includes a prefix at the beginning of each topic as a reference aid. The prefix is in the form of Roman numerals for the top level, Letter case | upper-case letters (in the alphabet of the language being used) for the next level, Arabic numerals for the next level, and then lowercase letters for the next level. For further levels, the order is started over again. Each numeral or letter is followed by a period, and each item is capitalized.
Some call the Roman numerals “A-heads” (for “A-level headings”), the upper-case letters, “B-heads”, and so on. Some writers also prefer to insert a blank line between the A-heads and B-heads, while often keeping the B-heads and C-heads together.
If more levels of outline are needed, lower-case Roman numerals and numbers and lower-case letters, sometimes with single and double parenthesis can be used, although the exact order is not well defined, and usage varies widely.
The scheme recommended by the MLA Handbook,<ref name=“MLA 2009”>
</ref> and the Purdue Online Writing Lab,<ref name=“Purdue”>
</ref> among others, uses the usual five levels, as described above, then repeats the Arabic numerals and lower-case letter surrounded by parentheses (round brackets) – I. A. 1. a. i. (1) (a) – and does not specify any lower levels,<ref name=“MLA 2009” /><ref name=“Purdue” /> though ”(i)“ is usually next. In common practice, lower levels yet are usually Arabic numerals and lowercase letters again, and sometimes lower-case Roman again, with single parentheses – 1) a) i) – but usage varies. MLA style is sometimes incorrectly referred to as APA style,<ref>For example:
</ref> but the Publication Manual of the American Psychological Association | APA Publication Manual does not address outline formatting at all.