从speedsolving上面摘的:
Slice Turns
On the 3x3x3, slice turns are popular in algorithms, although they are never needed in scrambling. These moves are defined in a very inconsistent way, so watch out. The possible slice moves, which can again be modified with ' or 2, are:
M - a move of the slice between R and L, in the same direction as an L turn.
E - a move of the slice between U and D, in the same direction as a D turn.
S - a move of the slice between F and B, in the same direction as an F turn.