Okay, I take your point. (no pun intended, tee-hee).
What I was looking for was a wildcard character that amazing charts could automatically convert into pounds and ounces.
You are right and I take my comment back -- 8.5 pounds should not convert into 8 pounds, 5 ounces.
However, I am not crazy about the three columns, as it seems to take an inordinate amount of screen real estate.
So, here is my alternate proposal -- let entering "8#5.5" be automatically rendered as 8 pounds 5 ounces, and let "8.5" be rendered as 8#whatever ounces, as you said.