(By Matthew S. Dryer): "This map shows the position of interrogative phrases in content questions. Content questions are questions that contain an interrogative phrase, like the elements in boldface in the English examples in (1)... Content questions differ from polar questions (see Maps 92A and 116A) in that they elicit a specific answer other than ‘yes’ or ‘no’, and in containing interrogative phrases. All languages have a set of interrogative words that are characteristic of content questions, though in many languages they are identical in form to indefinite words (like someone in English) (see Map 46A). These interrogative words typically belong to different categories (interrogative pronouns, interrogative adverbs, “interrogative adjectives”, “interrogative verbs”). Because most interrogative words in English begin with wh-, content questions in English are often called wh-questions. Although interrogative phrases often consist of single words (interrogative pronouns or interrogative adverbs), they may contain additional words, as in which book in (1b)."