Excellent link Mike, thanks.
Bird, yeah I like the non-technical meaning better as it directly relates to the type of engine so is easier to remember.
Well what do you know about that, the Amsoil Distributor is wrong. Just goes to show you, you can't always believe something somebody tells you just because they SEEM to be knowledgeable. On the other hand he may also just prefer to remember the difference that way also. I'll have to ask him next time I buy some Yukon GOLD !