Descriptive notation abbreviated to the first letter of its name: K for king, Q for queen, R for rook, B for bishop, P for pawn. Knight begins with the same letter as king, so it is abbreviated to either "Kt" (used in older chess literature) or "N". "N" is used in this article. In 1944 "Chess Review" received many letters debating the change from Kt to N . In descriptive notation each square has two names, depending on Black's or White's viewpoint. Each is given a name corresponding with the piece that occupies the first at the start of the game. Thus
Progressive chess move number (leading to notation in progressive chess like 1.e4 2.e5 Nf6 3.Bc4 Qh5 Qxf7#). In this way, the move number is equal to the number of moves in a series available to a player on that turn. There is another form of progressive chess, English progressive chess, which makes quite a significant change to the rules: within each turn, no piece may be moved twice until every other piece which has a legal move has moved once; no piece may move three times until every other piece which can has moved twice; and so on. These restrictions do not