Thanks all for the responses about alphanumeric characters and the use of that terminology.
I get that 123ABC consist of alphanumerical characters. However, does 123 consist of numerical characters? I would say it consists of numbers. Does ABC consist of alpha characters? I would say it consists of letters. In the documents I am working with, 123 is refered to as numerical characters and ABC is refered to as alpha characters. Here's what I'm talking about: "Move the part numbers that begin with a numerical character to the end of the list after the part numbers that begin with an alpha character." I'm just wondering how widespread this usage is. Are these terms just in my documents in my company, and I should make the correction, or do technical writers the world over use "alpha characters" to refer to letters and "numerical characters" to refer to numbers? Thanks! Deirdre