Carpentry and Woodworking - What does it all mean? (carpenter's square)

My use of a carpenter's square is pretty much limited to marking 90 and 45 degree angles and marking the cutouts for stair stringers. However, I do know that someone with a good knowledge of how to properly use this tool would rarely need to use a calculator. There tons of numbers on all edges of both sides of a square as well as almost the entire space between these edges, but I haven't the slightest idea as to what most of them mean.

Can someone please tell me what all the numbers and tables mean, or point me to a website that can. I've searched www.google.com to no avail.

Thanks

Here's some info

http://pumas.jpl.nasa.gov/PDF_Examples/11_07_00_1.pdf

http://www.bobvila.com/ArticleLibrary/Location/Workshop/CarpenterSquare.html

http://www.bobvila.com/ArticleLibrary/Location/Workshop/CarpenterSquare.html

http://www.bobvila.com/ArticleLibrary/Location/Workshop/CarpenterSquare.html

Hope this helps.