Fairy chess piece  A fairy chess piece, variant chess piece, unorthodox chess piece, or heterodox chess piece is a chess piece not used in conventional chess but incorporated into certain chess variants and some chess problems. Fairy pieces vary in the way they move. Because of the distributed and uncoordinated nature of unorthodox chess development, the same piece can have different names, and different pieces the same name in various contexts. Almost all are usually symbolised as inverted or rotated icons of the standard pieces in diagrams, and the meanings of these "wildcards" must be defined in each context separately. Pieces invented for use in chess variants rather than problems sometimes instead have special icons designed for them, but with some exceptions (the princess, empress, and occasionally amazon), many of these are not used beyond the individual games they were invented for. Today's chess exists because of variations someone made to the rules of an earlier version of the game. For example, the queen we use today was once able to move only a single square in a diagonal direction, and the piece was referred to as a "ferz". Today, this piece still starts next to the king, but has gained new movement and become today's queen. Thus, the ferz is now considered a non-standard chess piece. Chess enthusiasts still often like to try variations of the rules and in the way pieces move. Pieces which move differently from today's standard rules are called "variant" or "fairy" chess pieces. The names of fairy pieces are not standardised, and most do not have standard symbols associated with them. Most are typically represented in diagrams by rotated versions of the icons for normal pieces. The following text uses common names for the pieces described whenever possible, but these names sometimes differ between circles associated with chess problems and circles associated with chess variants. Many of the simplest fairy chess pieces do not appear in the orthodox game, but they usually fall into one of three classes. There are also compound pieces that combine the movement powers of two or more different pieces. An ("m","n")-leaper is a piece that moves by a fixed type of vector between its starting and destination squares. One of the coordinates of the vector 'start square – arrival square' must have an absolute value "m" and the other one an absolute value "n". A leaper captures by occupying the square on which an enemy piece sits. For instance, the knight is the (1,2)-leaper. Note that an ("m","n")-leaper is exactly the same thing as an ("n","m")-leaper, so that the knight can also be considered the (2,1)-leaper.