 Scores were expressed as percentages of a perfect maximum score and decreased as the tournament Category increased, thereby reflecting the strength of a player's opposition and the relative difficulty of the task.Tournament organisers could then apply the percentages to their own tournament format and declare in advance the actual score that participants must achieve to attain a GM or IM result (nowadays referred to as a norm).To qualify for the Grandmaster title, a player needed to achieve three such GM results within a rolling period of three years.