APS House Style :: Parentheses, Brackets, and Braces
Parentheses, brackets, and braces are used to set off material that is nonrestrictive or to alert the reader to specific or supplemental expressions. For example, there are parenthetical comments within sentences (to note information or interest) or that can be used to refer to specific figures/tables or sections (see Fig. 1 or Methods).
When writing braces in text, use the «lbrace» and «rbrace» codes. The brace symbols themselves are reserved for complex coding.
The following order is always used for nested marks: { [ ( … ) ] }.
Avoid heavy use of multiple, nested parentheses in text except when used to list chemicals or data. When possible, use commas or semicolons to set off parenthetical phrases. When in doubt, query the author.
Parentheses. References are usually cited at the end of sentences surrounded by parentheses (14). At some point, you may receive a manuscript where the author has used brackets around the reference citations instead of parentheses; in this case, it is helpful to globally change all "[ to (" and ") to ]" with MSWord (at the toolbar, click Edit, go to Replace, type in the specific mark to be changed, and replace each mark individually as the function proceeds).
Use parentheses to indicate doses or measurements so that a sentence doesn't begin with a number, e.g.,
Fluids (100 ml) were injected…
Close parentheses are used only for enumerations, e.g.,
We did the following things: 1) ate breakfast; 2) turned on the radio, which blasted stone-cold tunes…
Brackets. Brackets are used to enclose isotopic prefixes in the names of isotopically labeled compounds (e.g., [3H]inulin).
Brackets are also used to denote concentration, e.g., "[Ca2+]."
Braces. Mostly, you will use braces in the text only in heavily nested comments or within chemical formulas.
When writing braces in text, use the «lbrace» and «rbrace» codes. The brace symbols themselves are reserved for complex coding.
The Codecheck function double checks for you to determine if parentheses and brackets have been correctly used. It stops close to the location where it believes that the error occurs, and you have to examine the sentence and determine if it is correct.
In the same manner, the Codecheck function recognizes all information within typed braces { … } as a complex code. If this information is not in proper code format, it will query you to review it and place it in the correct format or to change the typed braces to «lbrace» and «rbrace» codes.