because each move has to be searched for visually. An amateur dan player would expect to play through a game of normal length in around 20 minutes. A player of professional level would take ten minutes, and could easily sight-read a professional game from the kifu. Stronger players can locate plays more easily because they often know where the next move is likely to be found. In most games, a small number of plays are at intersections that were previously occupied (this happens, for example, during a ko fight). Annotations by the side of the kifu give this information, usually in the form '57 at 51' or something comparable, indicating that move 57 occurred at the location formerly held by move 51. Game records are usually completed by information on the players' ranks, the date and competition data: location, winning player, and margin of victory. Many of the most important games are now available in machine-readable form, using one of a small number of digital Go file formats. This has great advantages in terms of ease of playing through games and lends itself well to database storage and archival. The common opinion is that playing games through on a board (rather than computer monitor) from a printed record is a qualitatively different---and preferred---experience. Much importance is given to the sensual aspects of the game: the heft of the game board, the players' viewing angle of the board, the feel of the stones, the sound of the stones when placed. Other formats Other notations There is no other universally-recognised notation comparable to algebraic chess notation for Go. There are several methods in use, including Using chess-like notation so on a 19x19 board points are a-t ('i' is excluded) for one axis, and 1-19 for the other. A similar system using Japanese numerals instead of letters. Using numbers for both axes, e.g. 3-4 is on the third row and fourth column from a corner. Pierre Audouard devised an elegant system using a letter a, b, c or d to designate the reference corner, plus one or two numbers to indicate the position relative to the corner. An equivalent system was used in ancient Chinese texts. Since the Go board is symmetrical with no particular sides, it makes no difference which corner is used as the reference point from which to count coordinates. Go file format Go file formats are used to record