Ace Combat
In the "Devil May Cry" and "Ace Combat" series, a grading system using letters are used. In Devil May Cry, the rating goes from SSS to D, with SSS being the highest and D the lowest and with each letter being assigned a single word to represent its value (e.g. in "Devil May Cry 3", A stands for "awesome"). In "Ace Combat" the rating goes from S to C with S being the best and C the worst.