position and type of the tile played. The first character denotes the column into which the tile was played, and the second character denotes the row. Columns are numbered successively from left to right as @, A, B, ..., Z, AA, AB, ..., AZ, BA, ... and rows are numbered successively from top to bottom as 0, 1, 2, 3, ... The third character denotes the type of tile played; symbols were chosen based on the general shape of the tracks. Crosses/straights are denoted by "+" and the curved tiles are denoted by the forward slash ("/") or backslash ("\") characters, which represent the direction of the diagonal of the corners between unconnected sides. The rotational orientation of the tile played is determined unambiguously by the tile(s) adjacent to where it was played, so the orientation of the tile played does not need to be specified using this nomenclature system. Similarly, the forced-play rule determines any additional tiles played during that turn, so the forced tiles do not need to be recorded. However, because the first tile to be played determines the orientation (relative directions) of the game board, only two valid first moves are possible. The two valid first moves are: (denoted ), where the white track defines the top and left sides of the game board and the red track defines the bottom and right sides. (denoted ), where the white track defines the top and bottom of the game board and the red track defines the left and right sides. The third possibility would be: (which would be denoted ) is not a valid first move. Since the white path on a curved tile defines the top and left sides, if the curved tile is played as the first move in this orientation, the playing field is rotated by 90° clock-wise and the move would still be recorded as . In this notation system, because the @ column and 0 row are used for the leftmost empty column and topmost empty row, this "origin" point will change in the turn following a turn in which a tile was played (or forced) into the @ column or 0 row. For example, once the first move is made ( or ), that first tile becomes position A1 for the second turn, so if the second player plays a tile to the right of that first tile, the second move