Continuing in CORE Lore, #17 explains how in the Agerosh Illumin, days are referred to as Marks due to the some worlds being in the night time while others are in day during the same time in the calendar.

Arthadian Anthologies @msarthadian

#CORELore 17: When speaking of the Agerosh Illumin, the calendar was made to tell time for thousands of different worlds. Instead of saying days, most refer to them as 'marks' on the calendar. #newexpandinguniverse #scififantasy #writingcommunity #worldbuilding

3:52 AM ∙ Jun 10, 2022