USS 128, C-128; Subsets include Code128 Subset A, Code128 Subset B, and Code128 Subset C.
Overview
Introduced in the early 1980's, Code 128 is a high-density alphanumeric symbology. Many industries quickly adopted the format for its size and encoding abilities.
Encoding
Code128 can encode all 128 Standard ASCII values using a three-digit ASCII code, preceded by the character. For example, the carrot symbol ("^") corresponds to ASCII code \094. For a complete list of ASCII values, refer to the ASCII Table.
Structure
Code 128 has the following structure:
A start character.
Message encoded.
Checkdigit.
Stop Character.
Termination bar (bar+space+bar).
Requirements
Code 128 is a continuous, variable length barcode with multiple element widths and a checkdigit. All characters contain three bars and spaces for a total of 11 modules. Toolkit automatically calculates and applies the checkdigit.
For an open system, the minimum value of the narrowest element (X) is 7.5 mils and the barcode height is 15 percent of the length or 0.25 inches. You must use the greater of the two measurements. The leading and trailing quiet zone must be at least 0.25 inches.
Code128 makes use of three shift characters, A, B and C. These shift characters enable different meanings for each encoded character, increasing the amount of information you can encode in the barcode. Toolkit automatically applies the shift characters based on the encoded value.
