When a cel is placed into the layup coordinate system (this is the ``placement'' method for cels or layers), a scale (s) is specified. This is the size in layup coordinates that the characteristic dimension of the cel should appear. This should be fairly intuitive -- if you want to place a character on the screen, you simply specify how tall they should appear on screen. The position (q) is also specified, which is the point (in layup coordinates) at which the pivot (p) of the cel should appear. The angle (a) indicates the (counterclockwise) rotation of the cel before it is placed.
Since the rotation process is somewhat intensive, it should be noted that excessive use of rotated cel placement in animations will result in slowdowns or pauses in the animation on slower machines. Because these will be cached, repeated uses of the same angle and scale will reduce this problem (with respect to using slightly different ones). The tolerance for substituting an existing cached rotation is one of the user-tunable parameters for AutoManga.