Ordering a neck - how can I specify what I want based on a neck I have?

How do I determine if a neck is a U, C etc. How do I tell if it's medium/fat etc? I would like to be able at times to order necks that are identical to other necks but I'm not sure how a neck is measured /specified.

Here are some measurements
http://www.allparts.com/Telecaster-Necks-s/265.htm

http://www.tdpri.com/forum/archive/index.php/t-158679.html

A contour gauge and a set of calipers will tell you everything you want to know, and it is extremely accurate. No guesswork. You can buy both at any hardware store ive ever been in.

Most companies that make necks will likely already know. People could just call them up and let them know what model guitar they are trying to reference. The measuring and math, in most cases, has already been done - it's their business.

I've done some searches on google and as Colt mentioned using calipers... and found all of the info I wanted - it's just not all in one place.

Thanks guys

Here are some measurements
http://www.allparts.com/Telecaster-Necks-s/265.htm

http://www.tdpri.com/forum/archive/index.php/t-158679.html

Those are handy. Here's a couple other links; the first is excellent.

http://www.tdpri.com/forum/telecaster-discussion-forum/313567-neck-profile-thread-post-your-measurements.html

http://www.tdpri.com/forum/telecaster-discussion-forum/186813-neck-profile-dimensions.html