two premium squares was to be compounded multiplicatively. The previously unspecified penalty for having one's play successfully challenged was stated: withdrawal of tiles and loss of turn. The major changes in 1976 were as follows. It was made clear that the blank tile beats an A when drawing to see who goes first. A player could pass their turn, doing nothing. A loss-of-turn penalty was added for challenging an acceptable play. If final scores are tied, the player whose score was highest before adjusting for unplayed tiles is the winner; in tournament play, a tie is counted as half a win for both players. The editorial changes made in 1989 did not affect gameplay. The major changes in 1999 were as follows. It was made clear that: a tile can be shifted or replaced until the play has been scored, a challenge applies to all the words made in the given play. Playing all seven tiles is officially called a "bingo" in North America and a "bonus" elsewhere. A change in the wording of the rules could have been interpreted as meaning that a player may form more than one word on one row on a single turn. Rules Notation system In the notation system common in tournament play, columns are labeled with the letters "A–O" and rows with the numbers "1–15". (On Scrabble boards manufactured by Mattel as well as on the Internet Scrabble Club, rows are lettered while columns are numbered instead.) A play is usually identified in the format xy WORD score or WORD xy score, where x denotes the column or row on which the play's main word extends, y denotes the second coordinate of the main word's first letter, and WORD is the main word. Although it is unnecessary, additional words formed by the play are sometimes listed after the main word and a slash. When the play of a single tile forms words in each direction, one of the words is arbitrarily chosen to serve as the main word for purposes of notation. When a blank tile is employed in the main word, the letter it has been chosen to represent is indicated with a lower case letter, or, in handwritten notation, with a square around the letter. When annotating a play, previously existing letters on the board are usually enclosed in parentheses; alternatively, the number of tiles placed on the board can be