Advancing/ Retarding Camshaft

LXguy said
Bottom of the page here has some good info:

http://www.lunatipower.com/Tech/Cams/CamSpecTerms.aspx

Well, actually the whole page has useful info, but the bottom has what you're specifically asking about.

Thanks for the link. That breaks it down and makes it really easy to decide on which direction I will be going in.