Still, use the centers as reference, but don't worry about their orientation until the cube is completely solved. Once the cube is solved, the following moves can be used to rotate the middle-center pieces of specific sides. In order to describe these moves, I need to define two new moves in addition to the old ones. The new moves are used to describe rotations of the middle slices, both the horizontal slice between the top and bottom sides, and the vertical slice between the left and right sides. V refers to the vertical slice sandwiched between the left and right sides.
H refers to the horizontal slice sandwiched between the top and bottom sides.
Remember, each side descriptor refers to the side with respect to the figure the move is referenced to. As before, numbers describe how to rotate a side, clockwise if 1, counterclockwise if -1, and 180 degrees if 2. Look directly at the side described to determine which direction is clockwise. To further clarify this notation, Move 1 has detailed accompanying figures to better describe it. Move 1 rotates the piece clockwise, while the Reverse of Move 1 rotates it counterclockwise.