Cat 1 :Fatal -
Continued operation is impossible. Machine power must be
switched off for at least 10 sec. If the error reappears, it should be
remedied. If error doesn't reappear, all should be O.K.

Cat 2 :Non-fatal -
Operation can continue. Error messages remain when the
error has disappeared. Messages must be acknowledged by pressing STORE. If
the error persists, the machine can still be operated.

Cat 3 :Non-fatal -
Operation can continue. Error messages disappear when
the error has disappeared. Messages can be acknowledged by pressing STORE,
even though error may still persist.