During the course of cent production, obverse and reverse dies may rotate with respect to each other.  This rotation may be observed when turning a coin over and noticing the reverse rotated either clockwise or counter clockwise in relation to the obverse.  While writing this reference, I will indicate die rotations of 5 degrees or greater in the description of die pairs.  However, die rotations of 20 degrees and greater will be listed in this index.  The degree of die rotation and the rarity are factors in determing the premium for coins with degrees of rotation greater than 35 degrees.