It is not just the ability of the boots to kick off ice or the prop heating to keep the props reasonably clear.
This is all true Pace, but I was just highlighting (obviously not very clearly) the absurdity of the definitions.
Moderate icing is
defined as a level of icing that necessitates de-icing equipment. It really doesn't make sense to have certification of de-icing equipment for "light icing". If the equipment is necessary and can cope with the conditions, the icing is "moderate". If it can't cope with the conditions, the icing is "severe".