A COBOL word is a string of not more than 60 characters, which forms a user-defined word or a reserved word. Each character of a COBOL word is selected from the set of letters, digits, underscores, and hyphens. Hyphens or underscores may not appear as the first or last character. When used in COBOL words, lower-case letters are treated as if they were upper-case, and underscores are treated as if they were hyphens.