Alternative Calendar: Measured from the landing of the Pallas Republic’s colony ship on SecLand. Most calendar apps list both the Terran years and SecLand years since then simultaneously, with the genetic ancestral homeworld listed on top.
SecLand has a year of 319 days, during terraforming strategic use of nuclear explosives were employed to accelerate the planet’s rotation to the day/night cycle Terran life had evolved to. After much deliberation the New Pallas authorities decided to give SecLand a calendar of 15 20-day months and one month with 19 days, at the end of the year.
Every other planet has its own local calendar as well, the apps tend to have an option for manual entry for when downloading one from the mesh isn’t an option.