Posted by pinotfan on 4/7/2012 7:58:00 PM (view original):
The plural of acronyms or initialisms is formed by adding an 's' to the entire acronym/initialism, so the plural of RBI is RBIs.
Sorry, but I think it does not work that way. RBI is both plural and singular. "He led the league with 112 RBI." "In yesterday's game, he had two hits and one RBI." The plurality is determined by context. You would never write "run batted ins."
Nevertheless, your approach would not be misunderstood, and manuals of style (MOS) tend to be silent on this question.
So, have it your way. I'll strike this one from my list of pet peeves.
4/10/2012 12:51 PM (edited)