Well, I have a CPL (H) and I never knew ANY of that !!!!.
So there you go,
Tonic Please - it sounds like heaps of us have benefited from your "stupid question".
Keep it up, I could definitely do with learning more!
(and Yes, I
DO google, but with the 1,657,875,998 pages that you get in response, I can certainly see why he came in here and asked.)