In other bar codes, one character can express one type of data. In CODE-128, through the selective use of the start character, one character can express three types of data in any position.

• Selective Start Characters
  
  

  Start Code - A	=	following characters are expressed using full-ASCII.
  Start Code - B	=	following characters are expressed as a 1-digit alpha-numeric or a mark.
  Start Code - C	=	following characters are expressed as a 2-digit number.

Change in Data Content By Start Character

• Code Set Character
  
  

  Code - A	:	changes the type of following characters to full-ASCII.
  Code - B	:	changes the type of following charactesr to 1-digit alpha-numeric.
  Code - C	:	changes the type of following characters to 2-digit numbers.

• Shift Character
  
  alters only the following single character from A --> B, B --> C, or C --> A, then back to the original type code.

• Function Character
  
  a character for special definition; for example, by inserting FC1 after the Start-code character, it indicates that the data is coded in the UCC/EAN-128 format.
  (See UCC/EAN-128)

With its flexible functionality, it has been adopted as worldwide-common supplemental code for physical distribution.

Summary of Code-128 Symbol

Character Composition