of contact with the puzzle, usually causing the puzzle to be unstable, in which, upon turning, more pieces may become loose and possibly pop out too. PrimeA counter-clockwise move popularly denoted with a ', e.g. 'R-Prime', denoted as R', R-, , or Ri. Also (less commonly) known as "inverse" or "inverted". SliceThe four center pieces and four edge pieces between two opposite layers of the cube. On a cube with four or more layers, it refers to any of the layers of the puzzle that don't have corner pieces. Also refers '/' moves in Square-1 puzzles. A puzzle that uses colored plastic instead of stickers to indicate color. Most stickerless puzzles were forbidden in competitions prior to a 2015 update of WCA regulations. A subset of algorithms for F2L that allows the user to force all upper-face corners to be oriented correctly, or an OLL-Skip, while the last F2L pair can be solved with R U R' or L' U' L. SQ-1Abbreviation for Square-1. Sometimes used as 'Squan'. Turns per second – the number count of turns per second indicating how fast the cuber turns. , also known as +2A penalty of 2 seconds which is added to a solving time in official competitions when the cube is placed back on the timing pad with one or more faces misaligned 45 degrees or more. It can also be given in other cases, such as when the competitor starts the timer too slow or does not correctly stop the timer after finishing the solve. The world's fastest time for a puzzle to be solved in an unofficial (non WCA) event. Valk Last Slot. A set of 432 algorithms (216 if mirrors are not counted), that solves together the last F2L pair and all of OLL when this last F2L pair is already paired up. WBThe world's fastest time for a puzzle to be solved. This can either be a single attempt or a trimmed average, depending on context, and does not need to be achieved at an official WCA competition. This usually has to be done on trust since verifying someone's solve they did at home which was not recorded is not really possible, although someone who has never officially competed claiming to have solved a 3x3x3 in under 3 seconds is unlikely to be believed. WCA World Cube Association, the international governing body for official cube competitions. , also known