No problem, gil.
The bead seat is where the tire seats on the wheel and it's also the dimension that determines the rim's specified diameter. The T&RA & JATMA manuals will provide diagrams that outline common wheel terms like the bead seat, dropwell, flanges, etc., so you can use those to educate yourself a little further in that regard.
Google worked great for me, finding both organizations websites:
Tire and Rim Association:
JATMA:
Hopefully, that will get you started in the right direction. I think the manuals are actually called yearbooks. T&RA has another design guide manual, but you might have to call them in order to get it.
The organizations are specific to certain regions around the world. T&RA is for the USA, JATMA is for Japan and there is one other organization for Europe (see the thread right below yours). If your wheels are aftermarket and only being sold in the US, don't worry about getting the other manuals because those won't apply here in the US.
Tim Flater
Senior Designer
Enkei America, Inc.
Some people are like slinkies....they don't really have a purpose, but they still bring a smile to your face when you push them down the stairs.