Q. Hi. In Chicago Style, are “T” and “F” acceptable for “True” and “False”? The document is simple questions with T and F answers.
A. If you mean capital letters T and F without periods, then yes. Chicago style requires periods with initials in names—as in “F. Scott Fitzgerald” and “T. S. Eliot”—but not with other types of capitalized initialisms (most of which include at least two letters, as in “US”; see CMOS 10.4). And though the abbreviations for t defined as “true” and for f defined as “false” are lowercase as main entries in Merriam-Webster, it would make sense to capitalize either one as a stand-alone, one-word answer.