Algebraic notation (chess) board. Thus each square has a unique identification of file letter followed by rank number. (For example, White's king starts the game on square e1; Black's knight on b8 can move to open squares a6 or c6.) Each piece type (other than pawns) is identified by an uppercase letter. English-speaking players use the letters "K" for king, "Q" for queen, "R" for rook, "B" for bishop, and "N" for knight (since K is already used). "S" (from the German "Springer") was also used for the knight in the early days of algebraic notation and is still used in some chess
Fairy chess piece here for "initial" in the description of the different types of pawns. The letter a is used here to describe again, indicating the piece can make the move on which it is prefixed multiple times, possibly with new modifiers mentioned behind the a, which then apply to the second 'leg' of the move. Directional specifications for such a continuation step should be interpreted relative to the first step (e.g. aW is a two-step orthogonal move that can change direction; afW is a two-step orthogonal move that must continue the same direction). To handle some frequently encountered special moves, e can