Calibration

From the White Wolf Wiki, the most complete White Wolf reference

In the calendars of Exalted, Calibration is a period of 5 intercalary days which belong to no time in the rest of the calendar. Calibration is generally regarded as a time of ill omen, and many tragic events from the beginning of the Usurpation to the disappearance of the Scarlet Empress have occurred on Calibration. The sorcerous spell for summoning a Demon of the Third Circle can only be cast during Calibration.