The International Month Calendar (IMC) is a subset of the International Calendar (IC), hence a standardized variant of the proleptic Gregorian calendar (PGC). The International Standard Month Calendar (ISMC) is a restricted subset of the IMC. It runs in parallel with the International Week Calendar (IWC). International Month Calendar Created byunknown at in for Week days7 Month weeks Quarter months 3 Year Quarters Cycle years 400 (97 leap) 400 ( leap)