Dating in the universe of Rogue Trader is quite difficult and extremely arcane, due to the ebb and flow of warp currents it is possible for two sectors of the Imperium to record different temporal dates relative to one another, while a vessel that traverses the Immaterium can often rapidly leave any form of conventional dating behind. All systems, vessels and settlements keep their own linear chronology according to a local dating standard, but a universal system is required in order to facilitate the collection of tithes, the movement of troops and the general running of the Imperium.

The game uses the official dating system of the Imperium as developed the Adeptus Terra for it's dating system, dates and times are recorded aboard the characters vessel as shipboard a calendar and are synchronized with the standard galactic calendar when the ship reaches port, this may result in considerable discrepencies between recorded dates. The storyteller also keeps a master calendar which is used to determine the 'official' dates behind the scenes in order to keep the chronology of the game flowing.

Imperial Standard Dating

An Imperial date is a date 'Anno Domini', but expressed in different terms to those we are used to. The most noticeable change is the suffix 'M' followed by a number. This is the millennium number. In Imperial terms any date between 2001 and 300 would be suffixed by M3. This suffix is normally emphasized by a full stop for clarity. The other numbers prior to the millennium number tell us the year, fraction of the year and the accuracy of the date.

A typical date may be expressed as 0150935/M41.

Year: The last three digits are the year within the millennium running from 001-000. 0150935/M41. is the year 935 of the forty-first millennium, described as the year 40935AD. When referring to a year in general terms, and where it is not necessary to include the year fraction or check number, it is acceptable to write 'year 935/M41'.

Year Fraction: For administrative purposes the standard year is divided into 100 equal segments; 001-000. This is a purely administrative convention and not part of everyday usage, although void faring vessels often use this as their official 'day'.

Check Number: The first digit in the sequence is the dating reference or check number. This check number is necessary due to temporal distortions which affect ships in Warp as well as worlds that are remote, or isolated, from Holy Terra. Its presence qualifies the accuracy of the date given in each case.

Prefixes 1 to 8 indicate widening 'grey areas' of a given item of data's surrounding origins. Prefix 9 is slightly different, it is used when, for instance, a source reporting from a world that doesn't use Imperial dating, needs to make a reference to that world's history. The historical date would carry the prefix 9.

  • 0/1 Terran standard date. Referring to an event which happened within Sol system.
  • 2 Direct. Source in direct psychic contact with Terra when date reference was made.
  • 3 Indirect. The source is in direct psychic contact with a class 2 source, but not Terra.
  • 4 Corroborated. The source is in direct psychic contact with a class 3 source, but not a class 2 source or Terra itself.
  • 5 Sub-corroborated. The source is in direct psychic contact with any corroborated source.
  • 6 Non-referenced 1 year. No psychic contact with a class 1-5 source when the reference is made. The reference does belong to a sequence beginning or ending with a date with a class 1-5 source. The unsourced time period is less than one standard year.
  • 7 Non-reference 10 years. This is an unsourced date in the same way as a class 6 date, but with an unsourced period of 1-10 years.
  • 8 Non-referenced more than 10 years. This is an unsourced date as for 7, but for an unsourced sequence of more than 10 years.
  • 9 An approximate date wit hno fixed coordinates at either end of a sequence, or a date drawn from non-Imperially date references.