No it's not a filter. I suspect DrawType of being a character field, since you will get an error trying to concatenate a logical field with a character one.

It's just a way of sorting the table using two fields of different type. The IIF() expression convert the logical field into a character one for concatenation.

HTH

>there is an index3 for a freetable that has as its expression "drawtype+iff(current,"T","F")"
>
>drawtype and current are both logical fields. i understand logical ifs. my question is what does a logical if do for you in an expression? is it a filter?