Code 128 uses the full 128 ASCII character set, can encode as many characters
as desired, and is designed to be ultra-high density. Code 128 is capable of displaying
2 digits with one set of bars (known as double density, or Subset C).
CODE 128-B
This encoding can represent all of the printing ASCII characters, from the space
(32) to DEL (127). The checksum digit is mandatory in this encoding.
CODE 128-C
The "C" variation of Code-128 uses Code-128 symbols to represent two
digits at a time (Code-128 is made up of 104 symbols whose interpretation is controlled
by the start symbol being used). Code 128-C is thus the most compact way to represent
any even number of digits. The encoder refuses to deal with an odd number of digits
because the caller is expected to provide proper padding to an even number of
digits.
