I just tried the search feature on the Tomato database and found a possible source of confusion. When I specified either "round" or "beefsteak" as the fruit shape, I got the list of results I expected, but when I clicked on both "round" and "beefsteak" instead of getting a consolidation of those two lists, I got no results. Likewise, if I choose both "determinate" and "indeterminate" I don't get anything. Apparently the choices within each category are combined with an 'AND' logical operator, not an 'OR'.
While such results make sense (fruits can't be both round and beefsteak shaped), first visitors to the database (like me!) may expect both choices to be combined, and be confused. I would suggest that your instructions suggest only making one choice in each category.
While it is just a little more work making separate searches for multiple choices, if it would not be too much trouble to change the search coding to use the OR logic within categories, that would be appreciated.
If I have misinterpreted the search actions, I apologize.
