Decision on amount of Ice
A seemingly meaningless document. The restrictions in the AFM are what you are required to follow. The only possible use for this instrument would be for an aircraft that does not have guidance in the AFM. All Boeing and Airbus products do. If your aircraft does not have a similar statement I would follow the advice of the major manufactures as outlined in the posts above and seek clarification from CASA that this is acceptable in terms of the instrument.