This is the standard nomenclature for the faces of the cube:
	L (Left)    : the side directly to the left of the front.
	M (Middle)  : the layer between L and R, turn direction as L (top-down).
	R (Right)   : the side directly to the right of the front.

	U (Up)      : the side above or on top of the front side
	E (Equator) : the layer between U and D, turn direction as D (left-right).
	D (Down)    : the side opposite the top, underneath the Cube.

	F (Front)   : the side currently facing the solver.
	S (Standing): the layer between F and B, turn direction as F.
	B (Back)    : the side opposite the front.

By convention, the cube is preferably oriented with:
	The red face to the right.
	The yellow face on top.
	The blue face in front.

As a result:
	The X-axis goes from the orange face to the red face.
	The Y-axis goes from the yellow face to the white face.
	The Z-axis goes from the green face to the blue face.