Once interstellar species began to trade with one another, common references of measurement had to be agreed upon. The Standards Convention of Gom met for the equivalent of thirty-two Earth years to decide and agree on these issues. Humans were not part of the convention as they had not yet ventured beyond their own solar system.
Basis: begining of Universe counting period at 1 × 1019 tics prior to the beginning of the Standards Convention (about 31.688 billion YearsEarth) and adjusted for another, classified event almost a billion years before the convention.
This was a purely arbitrary number agreed upon by the delegates. It was deemed necessary to have a singular constant to use as a zero place in figuring events in the universe. As most species figured the universe to be no older than 20 billion YearsEarth, the resulting number of tics (decimal) was rounded up to the next order of magnitude (1 × 1019 tics). This gave a period much longer than any civilization calculated as being the beginning of the known universe. Because an eighteen-digit number is unwieldy in ordinary circumstances, the period is subdivided into segments of 1 × 1015 tics called spans (about 3,168,895.541 YearsEarth).
Two _de facto_ units came into common use, but are not part of the official standard (yet…but it’s all but guaranteed). The kex is 1 × 105 tics (approx. 1.1574 DayEarth), and the wi is 1 × 1010 tics (approx. 31.69 YearsEarth).
Such niceties such as minutes, hours, days, and years are specific to each planet due to traditions, physical restrictions, and orbital mechanics. As a result, no world was compelled to adjust their local methods of time to the standard. The standard exists as a common frame of reference for conversions between civilizations for the purposes of information exchange and commerce, as well as for deriving/defining other forms of measurement.
As of the beginning of the story, the date is the 8,023 kex of the 1,931 wi of the 9687 span (all in base-10, of course, as that is the standard).