Imperial Dating System

Overview

The dating system of the Imperium is fairly complex in nature, and has been structured so as to deal with the vast amount of recorded history that exists in the 41st Millenium and the massive distances between settled human worlds, which can lead to long periods of isolation. Also the vagaries and time-warping effects of the Immaterium can make it almost impossible to keep accurate track of time over long journeys.

The Imperium has developed its own method of recording dates, which needs a bit of explanation. Most importantly, the years are always "Anno Domini" using the system of our own Gregorian Calendar, so the dates themselves are the ones that we are familiar with now. A typical date as Imperial scholars write it, would look something like 0123456.M41. Let's divide this code up to explain each part:

0 123 456 M41 = Check Number/Year Fraction/Year/Millennium.

Check Number

The check number refers to the accuracy of the date, required for clarity due to the common distortions of subjective linear time which occur while within the Warp, and inaccuracies in timing on remote or isolated Imperial worlds and star systems. Check numbers are listed using the following numeric classes:

• Class: 0/1 - Earth standard date. Referring to an event which happened within the Sol System. '0' is most commonly used to refer to an event which actually occured on Terra.
• Class: 2 - Direct. The source for the event the date records was in direct psychic contact with the Sol System or Terra when the date reference was made.
• Class: 3 - Indirect. The source for the event the date records was in direct contact with a Class 2 source, though not the Sol System itself.
• Class: 4 - Corroborated. The source for the event the date records was in contact with a Class 3 source.
• Class: 5 - Sub-Corroborated. The source for the event the date records is in direct psychic contact with a corroborated source.
• Class: 6 - Non-referenced, 1 year. The source for the event the date records is not in contact with a Class 0 to 5 source when the date reference was made, though it is a continuation of a timeline referenced by a Class 0 to 5 source.
• Class: 7 - Non-referenced, 10 years. As with Class 6 sources, but with a greater time span to allow for larger inaccuracies.
• Class: 8 - Non-referenced, 11+ years. As Class 7, though unsourced for a longer period of time.
• Class: 9 - Approximation. For when worlds using a non-Imperial calendar must reference an event in that world's history.

Year Fraction

For record-keeping, each year is divided into 1000 equal parts, numbered 001-000. Note that this is not generally used by Imperial citizens in everyday life, but is simply for administrative use by the Adeptus Terra.

Year

This is the year within the millennium, running from 001-999. For general dates, often only the year and millennium are included.

Millennium

This is the millennium since the birth of the ancient human religious figure Jesus Christ in which the event took place. As an example, the year A.D. 2010 would be represented very generally in the Imperial Dating System as 010.M3.