hi hilmar
thanks for this response, i hadn't thought of approaching from that angle. it could be a bit of work as there are quite a few instances of this dotted around the clipper app but it may well be the solution i need.
i'll give it a go, thanks again.
barry

>In general, built-in functions have a higher priority than UDFs. Therefore, I don't think what you desire is possible. Perhaps you can find another replacement expression in Clipper - for instance, a UDF with a different name, that invokes DESCEND() (in Clipper), and then create a function with the same name, but a different internal structure, in VFP.