Sometimes I'm not that happy being part of such an egocentric country. It can be really embarrassing. I think it was under President Carter when there was a push in the USA to change over from the english system to the metric system. I remember being very hopeful in those days, but once again emotion won over logic.
In the USA, "A.D." in relation to dates means anno domino, but I would venture that most any American under 30 years old wouldn't know that. I am quite confident that if you told them it meant "American date", they would believe you.
"at the office" is more correct in this case. If English words always had just one meaning, it would sure be an easier language to learn.