>I have an old DOS app running on a data collector opening
>Foxpro 2.6 dbf files, I am trying to modify it to work with
>VFP 5.0 files. Can it be done? Can I open VFP 5.0 dbf files from a DOS app?

No. But VFP5 can work just fine with 2.6 files. Don't MODIFY STRUCTURE within VFP, but if you do, they can be made 2.6 compatible again with COPY ... TYPE FOX2X.