[gsich]

Before Christian Era and Christian Era.

My main gripe with it is the low entropy. In BC/AD each letter is unique. Even if you only heared 1 letter you still know what was said.

[card_zero]

Seems like we could be using BCE/AV (for Anno Vulgi). This would be cromulent with how the BC/AD pair is half English and half Latin. And then for convenience and compatibility, shorten BCE to BC.