Rules Governing Masonic Calendar Dating

You hear it at Lodge: "A. L. 6012." What does that mean? Then you go to another Masonic organization and it is different.  Why? A.L. stands for Anno Lucis, or "In the Year of Light." Here is a summary of how and why the Masonic calendars work the way they do:

Ancient Craft/Symbolic "Master Mason" Lodges

Commence their era with the "traditional" creation of the world, calling it Anno Lucis (A.L.), "in the year of light." Add 4,000 years to the common era.  Thus 2012 becomes A.L. 6012.

Chapters of Royal Arch Masons of the York Rite

Date from the year the second temple was commenced by Zerubbabel, calling it Anno Beneficio (A.B.), "in the year of the discovery."Add 530 years to the common era. Thus 2012 becomes A.B. 2542.

Councils of Cryptic Masons of the York Rite

Date from the year in which the Temple of Solomon was completed, calling it Anno Depositionis (A.Dep.), "in the year of deposit."Add 1,000 to the common era. Thus 2012 becomes A. Dep. 3012.

Commanderies of Knights Templar of the York Rite

Commence their era with the organization of the ancient order, calling it Anno Ordinis (A.O.), "in the year of the Order." The Order was traditionally established in A.D. 1118. From the Christian Era, subtract 1118, thus 2012 becomes A.O. 894.

Scottish Rite

Similar to Ancient Craft except the Jewish chronology is used, Anno Mundi (A.M.), "in the year of the world." Add 3,750 to the common era.  Thus 2012 becomes A.M. 5772. After September, add another year.

(Source: Indiana Freemason)