Chapter 7 Bar Codes

Data Field

The bar code symbol uses a series of varying width bars and spaces to represent the entire ASCII character set. Each narrow bar or space is one element; each wide bar or space is three elements; each character in the data field has a total of sixteen elements.

Readable Data

The optional readable data field provides a readable interpretation of the bar code data. It can be printed above or below the bar code symbol.

Check Digit

The optional modulo-127 check digit can be inserted into the bar code to verify accurate scanning.

UCC/EAN-128

The UCC/EAN-128 bar code structure is shown in Figure 21 and described below.

 

 

 

OPTIONAL

 

 

 

 

CHECK DIGIT

 

SR, SC

 

 

 

 

POSITION

 

 

 

 

 

 

UPPER GUARD BAND

 

QUIET

START

DATA FIELD

STOP

QUIET

ZONE

CODE

 

CODE

ZONE

HEIGHT

LOWER GUARD BAND

OPTIONAL READABLE DATA FIELD

Figure 21. UCC/EAN-128 Structure

UCC/EAN-128 uses the same bar code and character set as Code 128. However, in UCC/EAN-128, the Function 1 character FNC1 immediately follows the start code. The FNC1 character has been reserved exclusively for UCC/EAN-128.

The UCC/EAN-128 data structure requires an Application Identifier (AI) at the beginning of bar code data. Each AI determines the format and length of the data which follows. See Table 73 for more detail.

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IBM 4400 manual UCC/EAN-128