Craft Masonry's calendar commences with the creation of the world and uses the term Anno Lucius (A.L.) - "In the year of Light." To arrive at this date they add 4000 to the common time, as the Earth was believed in conventional theology to have began in 4000 BC . Therefore the year 2001 becomes 6001.
Royal Arch Masons date time from the year the second temple was commended by Zerubbabel. Anno Inventionis (A.I.) ,which means "In the year of Discovery," is the terminology used by Chapters. This adds 530 to the common time, therefore the year 2001 becomes 2531.
Royal and Select Masters or Cryptic Masons date from the year in which the Temple of Solomon was completed. It is called Anno Depositionis (A.D.), which means "In the year of the Deposit" and adds 1000 to the common time. Therefore the year 2001 becomes 3001.
Knights Templar start their calendar with the formation of the order in 1118 AD. Anno Ordinis (A.O.), which means "In the year of the Order" is the terminology used. This deducts 1,118 from the common time; therefore the year 2001 becomes 883.
The Scottish Rite date the same as Craft Masons, except for the use of the Jewish Chronology. Anno Mundi (A.M.), which means "In the year of the World" is their calendar terminology and adds 3760 to the common time. Therefore the year 2001 becomes 5761.
Article from: http://www.mtararat44.org/content/view/44/57/
Related: Freemasonry & Secret Societies