With LabVIEw version 6i you can save VIs in version 5.0 format. However, in LabVIEW 4.1 there is no such function. What the situation is with other versions of LAbVIEW I do not know but I would guess that this is a new function and thus only available in version 6i. To save the VIs in version 6i you go to File/Save with options and select the radio button Save for previous (5.0). Hope this helps. /Mikael