Parentheses for supplemental material, interruptions, and afterthoughts
Parentheses for series
Use parentheses to enclose letters or numbers labeling items in a series.
An alternative is to use a numbered list. Generally, numbered lists do not use parentheses to enclose the numbers.
Overuse of parentheses
Do not overuse parentheses. Rough drafts in particular are likely to contain more afterthoughts than necessary. You may find yourself tucking additional details into parentheses as you write a draft. You should revise such sentences so that the additional details no longer seem to be afterthoughts.
Numbered list
Style tip on punctuating parenthetical material
Exercise: Other punctuation marks
Related topics:
Lists
Commas with items in a series