Some crossword clues, called "straight" or "quick clues", are simple definitions of the answers. Some clues may feature anagrams, and these are usually explicitly described as such. Often, a straight clue is not in itself sufficient to distinguish between several possible answers, either because multiple synonymous answers may fit or because the clue itself is a homonym (e.g., "Lead" as in to be ahead in a contest or "Lead" as in the element), so the solver must make use of "checks" to establish the correct answer with certainty. For example, the answer to the clue "PC key" for a three-letter answer could be "ESC", "ALT", "TAB", "DEL", or "INS", so until a "check" is filled in, giving at least one of the letters, the correct answer cannot be determined.