>You can update data in old table fields, no harm for DOS; and you should not change data structure.
>
>If I need to do that - none of the tables have any primary keys - can't I just change the data structure in VFP and copy the result to TYPE FOX2X?

You can change table structures in VFP as long as you do not introduce any VFP features. No need to copy them back to FOX2X. You can use SYS(2029) to make sure that table type didn't change.