The Intergalactic Standard Calendar (ISC) is a calendar system employed by the Intergalactic Federation (IGF) in an attempt to standardize the way time is told across their tradespace. The calendar begins at ISC 0-1-1.000, indicating the first day that the IGF was officially ratified as an organization. Days and months are relative to Sonalos, the IGF 'Hub World'. Sonalos has 10 hour days, and takes 300 days to revolve around its star. Weeks are generally to be considered a measurement of 6 days, with 5 weeks in a month.
Dates are given in ISC YYYY-MM-DD.H format, with a decimal point indicating the tenth of the revolution in the case of hours / minutes / seconds. For example, ISC 387-5-12.325 is in the early morning of the 12th day of the 5th Month of the 387th year since the IGF was ratified, relative to Sonalos. Generally speaking, the decimal is irrelevant except when talking about time-sensitive planning, such as the exact route to navigate through Ihmir's Stadium without getting hit by an asteroid.
Lorekeeping Notes
For ease of reading long-term, sub-calendars of the ISC have been created for all planetary systems with events. As the lore of the Caelum Galaxy expands, it is doubtful only one calendar will suffice to contain all entries in a somewhat readable format.