Unlike the Terran calander used by the Empire and the Confederation rebellion; the Talesian calander, and that of all worlds allied with the Talesian Star Republic is a pure numeral based calander. There are no months; time is measured only by the year and the day of the year in numerical format.
When the Talesian Great War ended in nuclear apocalypse, civilization broke down and shattered many records of ancient Talesian history; starting a new era which in turn reset the new Talesian calander to 001.001. Most sccurate surviving historical records begin at or just prior to this point; leaving many details of Talesian society or goverments before the great war fuzzy at best. Much of this is intentional, with the start of the new era ushered in by the destruction of the old regime; the history that is taught to all but the Scholars on Talesia starts with the end of the Talesian Great War.
Talesian Standard Year: A standard year in the Republic is based around a year (one rotation around the Talas star) of Talesia. The TSY is the basis for the TSDT. Talesia has a similar orbit around the sun as Earth, but adds another 55 days to a standard calendar year, making the Talesian year 420 days long. Just like Earth, the orbit is not precisely 420 days; instead a leap year occurs every 5 years; which adds an additional day to the calendar; marking the last date of the year as .421 rather then .420.
Talesian Standard Time: Talesia has a rotation nearly identical to that of Earth. Talesians have adopted a 24 hour day nearly identical to what humans use.
Format of TSDT: [year].[date] and [year].[date].[hour]:[minute]. Example: The Talesian year 240 on the first day of the year on the first minute of the year comes out to: 240.001.00:01 in the TSDT format. TST is therefore just used when referencing the time alone, which follows the time format of 00:00 hrs.