APS House Style :: Punctuation
Colons are used before a list not immediately preceded by a verb or preposition, such as "We like fruits: apples, oranges, and bananas."
Colons are always used after the terms "the following" or "as follows."
To separate a complete concepts from a following illustrative word, phrase, or clause, for example, "At present, there are two opposite views on psychopharamacology: depression or enhancement."
To express a numerical ratio of components, for example, "phenol-chloroform-alcohol (24:24:1)."
When needed inside parentheses to associate data with a specific group, for example, "We found a significant difference in flight direction between English and African swallows laden with coconuts (English: 1 mile/h straight down vs. African: 1 mile/h northward).
In figure legends after a specific panel, for example, "Fig. 1. A: mine; B: yours."
If a long explanation follows in a list (whether numbered or unnumbered), a period is acceptable instead of a colon.
In figure legends after a specific panel that is then introduced in two parts, for example "Fig. 1. A: mine. Top, what I took; bottom, what I was given. B: yours."
Avoid having two sets of colons together; instead, used another type of punctuation or construction. For example, change
The bear went over the mountain (north: 2 ft: 5 min; south: 10 ft: 25 min).
to
The bear went over the mountain (north: 2 ft, 5 min; south: 10 ft, 25 min).
or
The bear went over the mountain (north: 2 ft for 5 min; south: 10 ft for 25 min).