Instrumenter og udstyr, der allerede er godkendt, skal ikke overholde en revideret ETSO eller en anden revideret specifikation end ETSO, medmindre der foreskrives et krav med tilbagevirkende kraft.
Instruments and equipment that have already been approved do not need to comply with a revised ETSO or a revised specification, other than ETSO, unless a retroactive requirement is prescribed.