I had indicated a bounty of 50 points for an outstanding answer. I wanted to increase the amount to 100 points, but it seems that the 50 was locked in.
So after waiting the requisite 24 hours, I went to award the additional 50 points. A pop-up indicated that I could irrevocably give 100 bounty points.
Please forgive my confusion: does that mean 100 cumulative points (my initial 50 plus 50 more) or 100 additional?