For this:
For any record, I need to compare the number in those 3 fields to each other, and choose the largest number and group by that rating.
More if statements are needed, four for each of the three items.
flam4: iif([Nfpaflammability]=4,1,0)
Flam3: iif([Nfpaflammability]=3,1,0)
And so on...