I know if you use radio button group then the user can only check one box out of whatever many is in the group. But say if your using 4 checkboxes but you want the user to be only allowed to pick one then I am assuming you have to use code. Now do you use FormCalc or Javascript? and then what is the code to do that? Basically if they click on checkbox1 then checkbox2, 3 and 4 should be blank then if they click on checkbox2 then checkbox1, 3 and 4 should be blank.