>select B
>REPLACE f1 WITH A.f1

>You can actually just "Replace B.f1 with A.f1" without changing the current >work area. This is significant in scan..endscan and do..enddo loops where >you'd have to keep switching the work area for every iteration of the loop.

I've actually run across a lot of time this didn't work (for whatever reason). I have found the following to work better:
replace f1 with a.f1 in B