editors consider these symbols unnecessary. A few writers have used unusual combinations of question marks and exclamation points (e.g. "!!?", "?!?", "??!") for particularly unusual, spectacular or controversial moves, but these have no generally accepted meaning and are typically used for humorous or entertainment purposes. Sometimes annotation symbols are put in parentheses, e.g. "(?)", "(!)". Different writers have used these in different ways; for example, Ludek Pachman used "(?)" to indicate a move that he considered inferior but that he did not wish to comment on further; Simon Webb used it to indicate a move that is objectively sound, but was in his opinion a poor psychological choice; and Robert Hübner (see below) used it to indicate a move that is inaccurate and makes the player's task more difficult. Alternative uses Some writers take a less subjective or more formalized approach to these symbols. Nunn's convention In his 1992 book Secrets of Rook Endings and other books in the series (Secrets of Minor-Piece Endings and Secrets of Pawnless Endings), John Nunn uses these symbols in a more specific way in the context of endgames where the optimal line of play can be determined with certainty: {| |- style="vertical-align:top;" ! ! | The only move that maintains the current evaluation of the position: If the position is theoretically drawn, this is the only move that does not lose; if the position is theoretically won, this is the only move that secures the win. An "!" is used no matter how trivial the move in question; the only exception is if it is the only legal move. |- style="vertical-align:top;" ! !! | A particularly difficult-to-find "!" move. |- style="vertical-align:top;" ! ? | A move which negatively affects the evaluation of the position: If the position had been drawn before the move, it is now lost; if won before the move, it is now drawn or lost. |- style="vertical-align:top;" ! ?? | An obviously bad "?" move. |- style="vertical-align:top;" ! !? | A move which makes the opponent's task harder or one's own task easier; for example, in a theoretically lost position, a move which forces the opponent to find several "!" moves in order to win. |- style="vertical-align:top;" ! ?! | A move which makes the opponent's task easier or one's own task harder; for example, in a theoretically won position, a move which requires several subsequent "!" moves in order to