a7.1. With the exceptions outlined below, words formed with the addition of a prefix (anti-, bi-, co-, inter-, intra-, multi-, post-, pre-, sub-, ultra-, un-, under-, etc.) do NOT take a hyphen and are written as one word. Words commonly mispunctuated include: biweekly, coauthor, cocurricular, interdepartmental, intracampus, multicultural, preregistration, postgraduate, postmodern, and semiannual. When in doubt, refer to Merriam Webster's Tenth Edition.
a7.2. Separate with a hyphen if the word to which the prefix is appended is capitalized (un-American, anti-Reagan, pro-Shiite).
a7.3. Separate with a hyphen if necessary to avoid repetition of letters (anti-intellectual, re-employ). (See also Hyphens.)
a7.4. The prefix co- takes a hyphen when the word that follows begins with an "o" such as co-own, co-occurrent, co-official. NOTE: This is a guideline that differs from AP Stylebook.
a7.5. The prefix pro- takes a hyphen when used to denote a position (pro-choice, pro-environment).