select 1
scan
   select 2
   scan
      ? field2
   endscan
   ? field1
endscan

As far as I can tell (without running it right now), this should throw an error unless there is a field1 in the table in work area 2. We've been discussing that ENDSCAN automatically re-selects the alias associated with the SCAN. If your code works, then it implies that the re-select took place before the ENDSCAN (unless you are using the alias.fieldname which is not apparent from the above).