Code 128
Code 128 is a linear bar code symbology capable of encoding the full 128-character ASCII character set and extended character sets.
The characteristics of Code 128 are:
a) Encodable Character Set:
(1) All 128 ASCII characters, i.e. ASCII characters 0 - 127 inclusive, in accordance with ISO 646.
(2) Characters with ASCII values 128 - 255 may also be encoded.
(3) 4 non-data function characters
(4) 4 Code Set selection characters
(5) 3 START characters
(6) 1 STOP character
b) Code type: Continuous
c) Elements per symbol character: 6, comprising 3 bars and 3 spaces, each of 1, 2, 3 or 4 modules in width (STOP character: 7 elements comprising 4 bars and 3 spaces)
d) Character Self-checking: Yes
e) Symbol Length: Variable
f) Bidirectionally Decodable: Yes
g) Symbol Check Character: One, mandatory
h) Data Character Density: 11 modules per symbol character (5,5 modules per data character in Code Set C)
i) Non-data Overhead: Equivalent to 35 modules
Code 128 Code Sets
a. Code Set A includes all of the standard upper case U.S. alphanumeric keyboard characters and punctuation characters together with the control characters, (i.e. characters with ASCII values from 00 to 95 inclusive), and seven special characters.
b. Code Set B includes all of the standard upper case alphanumeric keyboard characters and punctuation characters together with the lower case alphabetic characters (i.e. characters with ASCII values from 32 to 127 inclusive), and seven special characters.
c. Code Set C includes the set of 100 digit pairs from 00 to 99 inclusive, as well as three special characters. This allows numeric data to be encoded as two data digits per symbol character, at effectively twice the density of standard data.
Code 128 Special characters
The last seven characters of Code Sets A and B (character values 96 - 102) and the last three characters of Code Set C (character values 100 - 102) are special non-data characters with no ASCII character equivalents, which have particular significance to the bar code reading device. | 
