In 666 – 667 A.D. by the order of Armenian Catholicos Anastas Akorretsi the famous scientist of the time Anania Shirakouni created a new textbook
(called Qnnikon) for the Armenian higher schools (universities) including all the seven disciplines of the time (trivium and quadrivum). The calendar was also included in this textbook and was called Tomar-The Calendar.Anania’s Tomar (The Calendar) consisted from theoretical and practical parts. In the first – theoretical part he substantiated the positions of the main feasts of Armenian Apostolic Church. Particularly he theoretically proved the truthfulness of the positions of the days of Nativity and Easter used by Armenian Church. The applied part of Anania’s Calendar consists of two main large tables – The Kharnakhoran and the 532-year tables. The Kharnakhoran was a set of 12 large tables, each on two pages, representing 12 months of Roman calendar. These tables were created and used to synchronize and parallel represent the calendars of 14 Christian nations (Romans, Greeks, Syrians, Hebrews, Arabs, Macedonians, Egyptians, Ethiopians, Athenians, Bithynians, Cappadocians, Georgians, Albanians (this refers to the Caucasian Albania), and Persians). The 532-year tables were created to give all the major church feasts and other important calendar data for 532 years from 581 to 1113 AD. In these tables all the data was given parallel both in terms of Armenian and Roman calendars. So, these tables made it possible to pass from Armenian calendar to the Roman calendar and vice versa. Thus, by means of these two main tables (the Kharnakhoran and the 532-year tables) it was possible to synchronize Armenian calendar with the calendars of all Christian nations that was the demand of the apostolic laws.