Characters possess Attributes and Skills rated between 1 and 100 on a percentile die (d100) or two ten-sided dice (2d10). Skills can be modified to a rating above or below these limits (i.e. under 1 or over 100, with open-ended MERP options to add or subtract additional d100). An attack roll consists of a percentile roll, to which the attacker's skill rating and appropriate attribute rating are added and the defender's dodge rating is subtracted. The result is compared to the defender's armor type and looked up on a table to determine success or failure. A separate critical table is used in the initial chart result called for it.