'Qa1 x d4' move

The moving piece can only move to any square before it in the special chess moves. Suppose a white Queen is positioned on a1 (Qa1) and a black Bishop is placed on d4 (Bd4). If it is WHITE'S move then he can capture the Bd4, for this move one necessary condition has to be satisfied that the squares b2 and c3 should be empty. To do this, enemy BISHOP is removed and QUEEN of self side is to be placed at d4. We denote this move by 'Qa1 x d4' (or simply 'Qxd4'). This means 'The Queen at a1 captures (something) at d4'. If there was no capture we would write 'Qa1 - d4' (or simply 'Qd4').