"BP"
https://www.thoughtco.com/bp-how-do-archaeologists-count-backward-170250I got trapped into going through this thread and wondered about that. I guess "BP" avoids "AD" and "BC" and "CE" (Christian Era) and Julian Dates, etc, but seems like it would avoid confusion if a writer just said "years ago."
It's just another SAUONA (Smart Assed Use Of Needless Acronyms) which demonstrates laziness and is evidence of a childish "I know something you don't know, nyah-nyah!" mentality, or a slavish copying of a military style.
Or all three.
Communication, after all, is the goal of writing.
Even "minus 23ka" would have been better, and better recognized. Everybody knows what "ka" means, right?
Terry said that and he ain't takin' it back.
PS. I thought it was recommended somewhere, rather than bumping old threads to make additional comments, it was better to start a new thread quoting the relevant parts one is commenting upon. Can't find it, and it may be a rule from another board, but it sure makes sense.