2. English Language Punctuation - Apostrophe The functions of the apostrophe are to indicate possession; to form the plurals of abbreviations, characters, and signs; and to indicate omitted characters in contractions. The rules for forming the possessive case of nouns are presented in section possessive. An apostrophe is never used to form the possessive of a personal pronoun. We prefer to follow the GPO and to use the 's to form the plural of symbols, abbreviations, acronyms, designations, signs, numbers, and years: x's PMT's +'s 's M.A.'s 1970's C-130's 4's 60's Note: Chicago Manual of Style and WIT recommend that the apostrophe be used in such plural constructions only when necessary to avoid confusion. An 's is used to form the plural of a word referred to as the word itself, but the apostrophe is not necessary when the word retains its meaning: There can be no ands, ifs, and buts. (meaning no conditions) Punctuation There can be no and's, if's, and but's. (meaning the words cannot appear) The apostrophe indicates letters left out of contractions, for example, it's (it is), Gov't, and nat'l. Since contractions are rare in formal writing, such use of the apostrophe is also rare.
