Harlan
thanks for taking the time to explain this.
there are a few new elements for me to use. My initial efforts to solve
the op's question had lead me down OFFSET with an array call. However, as
you point out, MIN does not work.
Therefore, I now understand the use of the two COUNTIFs to mimic this
action.
I did solve the problem with a brute force UDF but I do like the idea of
using worksheet functions when I can.