I apologize if this is not the correct group for this question.

I have been researching barcode technologies and I currently believe Code
128 best meets our needs.

I need to encode a string of about of numbers, letters and special
characters into a barcode.

I am going to provide the data to our vendor and they will encode the
barcode on our mailers.

My question is about the checksum.

Is there a standard list of values for Code 128 ? It looks like some of the
vendors map out some of the characters to enhance their products. Where can
I download the data required to generate and lookup the checksum?

Is there a free Active X or anything that does the calculation for you?

Any help would be appreciated.