Kommunikations- og navigationsudstyr, der allerede er godkendt, behøver ikke at overholde en revideret ETSO eller en revideret specifikation ud over ETSO, medmindre der foreskrives et krav med tilbagevirkende kraft. ###>Communication and navigation equipment which has already been approved does not need to comply with a revised ETSO or a revised specification, other than ETSO, unless a retroactive requirement is prescribed.