Hello Bean: Now reading some answers - I understand your question was in English.
But when I first saw it, I thought in "Spanish" and just in case I tell you: AC (antes de Cristo which means Before Christ) and DC (despues de Cristo which means After Christ), and people refers to this to locate time of a determined event, but if you see translation to English - some people leaves the AC and changes all sense because meaning is opposite between both languages. For translators, this is an important issue to take into account.
Have a nice day
Carmen