DO WHILE .T.
  @ 05,07 GET  maccd       
  @ 06,07 GET  machddtls  VALID vcheck()
  READ
  IF LASTKEY()=27
    EXIT
  ENDIF
ENDDO


FUNC vcheck

command lines ...

* If ESCape is pressed here I need to reset the lastkey() value ELSE i am thrown out of the DO WHILE
RETURN