Widgeon,
yes, sort of. Ignore the old AS numbers as that was a different system. With EC designators, the first number is eithe 1 for civuil or 6 for Mil, the second is the weight category and the last digit is 0 for single engine or 5 for a twin. When the weight goes into double figures they add it to the first digit e.g the 12 ton EC-225.
(Bored in LGW waiting for a plane to Marseille!)