Off Center
   The most common error type for Indian Heads and every other denomination is the off center strike, the result of a coin being struck out of its collar and incorrectly centered with part of the design missing. The degree to which it is off center is measured in percentages, with the direction in which the coin moved denoted by the clock scale. Examples that are 50% off center and occur on a rare type coin in mint state, like the one below, are worth a premium.
1864 w/L on Ribbon/50% off center to 2:00/MS63BN