Hi mark,
Thanks ive used some of what you said and put it together in a way, makes it easier to understand. here goes.
Selections Trigger Expression 'IF(OR(FIND("A10", "market_name")>0, FIND("A11", "market_name")>0, FIND("A12", "market_name")>0), 0, IF(OR(FIND("A1", "market_name")>0, FIND("A2", "market_name")>0, FIND("A3", "market_name")>0, FIND("A4", "market_name")>0, FIND("A5", "market_name")>0), 1, 0))' is equal to 1.
the first part is because if you have A1, you need to discount the A10, A11 and A12 class first, otherwise it will bet on either, the second part will return 1 if true or 0 if not.
thanks
kev