 These are written as (for instance) Y168, or August Y168, and are dated to the year Earth first made contact with the Vulcans.A direct conversion to familiar Anno Domini dating is (purposefully) not given; however, the "Federation and Empire" rules state that Y0 should be somewhere between AD 2020 and AD 2090, the "Federation Commander" rules arbitrarily set it as AD 2400 (referred to in-universe as the Valkenburg Chronology) and consistently use 'AD' dates derived from that rather than use 'Y-year' nomenclature, while an option setting the date at 2063 (in line with the year of First Contact set in other "Star Trek" settings) is known as the Amin-Audeh Chronology.In all cases, it is stated that the actual date cannot be precisely known.