It's a good question, and nobody seems to have the definitive answer. I think you could make a good case for your interpretation, since it is after all what it says on your ratings page. But at the same time certainly all the UK and JAR legislation refers to years from date of issue, and the clock on that must surely start and stop ticking at the place of issue. I do appreciate that gives six monthly OPCs an extra hour's validity in the winter, and one hour less in the summer thanks to daylight savings time !
Re. your point about subtraction, for a new rating in the UK at least, you get from the moment you've passed the test, till midnight the day before a year's hence. The only bit you're 'losing' is from midnight to the moment you pass the test, and if you're worried about that, then schedule your checks for the earliest possible moment in the day ! Thereafter (again in the UK), you can revalidate up to three months in advance of the expiry with no loss to the original expiry date. In other words you're actually gaining three months rather than losing anything.
Last edited by puntosaurus; 14th Oct 2009 at 22:22.