The Common Era, also called Anno Domini, is a convention used on Earth to indicate if a year is before or after the start of the Gregorian calendar. Some humans prefer the former name, others the latter, but they both indicate the same thing.
Years before are marked BCE (Before the Common Era) or BC (Before Christ).
Years after are marked CE (Common Era) or AD ("Anno Domini").
As an example, the Roman emperor Tiberius lived from 42 BCE to 37 CE. The current year on Eamon (1200 YA) equates to 1984 CE / 1984 AD on Earth.
