This is a message I hope that Mr. Collins will comment on as well. It pertains to the 'known icing' restriction as it applies to IFR operations. I understand in the States, that the only restriction is in 'known icing' i.e reported by others, if the A/C is not certified for flight in those conditions. In Canada, on the otherhand it also applies to FORECAST icing as well. So,all forecasts show ICGIC ABV FRZ LVL (the typical disclaimer used on both sides of the border, which essentially precludes any operations in winter, where the FRZ LVL is well below the MEA. Now I understand bureaucratic constipation, but this does some a bit extreme - or does it? It is a fact that some icing WILL occur in clouds at temperatures below freezing, so shouldn't this be KNOWN ICING? I have seen comments in Flying Mag that appear to brush off this aspect of physics. If the flight (i.e. type certificate)restriction is 'not approved' in icing conditions, how can anyone justify ignoring it, just because no one 'reported' it. How much ice is too much? (I'm sure that there must be a pact among pilots to ignore and not report light icing, otherwise this would really throw a wrench into the works for everyone else in the area). This also brings up an interesting point that I'm sure the FAA or insurance company lawyers would use to their advantage in the right circumstances - if you saw light rime form on the temp probe, it is now known icing (to you at least), therefore you must exit the area immediately or you are flying in contravention of the type certificate and the regulations. Just some food for thought.