Code 128 is a high-density alpha-numeric symbology. It is able to turn your data, ranging from one character to 20 characters, into bars and spaces.
Your data can encode any character in the ASCII table, including uppercase alpha, lowercase alpha, numeric character, and control characters.
Code128 requires a check digit to be appended at the end. Most applications do that job for you automatically. But if you really want to do it by yourself, we have source code in Visual Basic and C language.
Code128 has three subsets:
Code128A,
Code128B and
Code128C.
Code 128A is used to encode uppercase alpha and control character.
Code 128B is used to encode uppercase, lowercase alpha and numeric data.
Code 128C is used to encode numeric-only data.
GS1-128 barcode is used to encode GTIN-14.