Q. I’m copyediting some storyboards for kiosk displays in a state park and in the description of a historical site, there’s reference to “2,500 BP.” I know what that means (now that I’ve looked it up), but why not just say “ago”? Should I assume the audience for these displays will know “BP,” or may I suggest simply saying “ago”? (I thought, “British Petroleum,” for Pete’s sake.)

A. It’s a good idea to change it, since visitors to state parks include many people who would have no idea what BP means. But don’t get your hopes up: it’s likely that the state has a style guide and that all its signs conform to that style.