 One advantage of such an antirealist move is that it can be used for both fictional sentences and external metafictional sentences. For Walton, what distinguishes the two cases is simply the kind of pretense that makes the relevant sentence fictionally true. In the former case, the game of make-believe that the relevant fictional context singles out is an authorized one; that is, it is a game authorized by what serves as a prop in that game (in the case of a literary game of make-believe, the text written or narrated by the storyteller); the prop dictates how things go in the world of that game. In the latter case, the relevant game of make-believe is an unofficial, albeit standard, one (1990: 417); in this case, there may be no constraints—none, at least, provided by the prop—that dictate how things stand in the world of that game (cf. Walton 1990: 51, 406, 409).