Something like this may work--you may need to aggregate the Capacity fields, if it makes sense to do that.  In that case, you'd just wrap each Capacity field in SUM(), like IF SUM([Capacity])>50... etc

if [Capacity] > 50 AND [Capacity] <=150 then "Small"

elseif  [Capacity] > 151 AND  [Capacity] <= 250 then "Medium"

elseif   [Capacity] > 250 then "Large"

else "none"

end

There may be more efficient ways to write this calculation, but I believe this will work.

You have to AND two comparisons

if  capacity >50  AND capacity <= 150 then  etc,...

Michel

No problem at all.