Bar Code Terminology

Bar Code Symbologies

Frequently Asked Questions

Character Set

What characters can be represented by the symbology.

Check Digit

This is the last character before the stop character and is calculated by a formula based on the rest of the data. It is part of some symbologies and is added to others to increase the security rate.

Continuous bar code

If barcode characters contain a space at the end of each character as part of it.

Density

Number of Data Characters per unit of length, usually inches.

Discrete bar code

If the spaces between characters are not part of each character.

Element widths

Number of different width elements in the bar code, two width or multiple width.

Fixed length

Bar code must have this many characters.

One dimensional bar code

Symbology that can be read by drawing a straight line through any part of the bar code is one dimensional.

Module width

Width of the narrowest element.

Nominal width

Width of the narrowest element.

Quiet Zone

This is the area to left and right of the bar code. It is required on all barcodes, otherwise any graphics, type or the edges of the item will be interpreted as a bar. For two dimensional bar codes it is all four sides. Violation of this rule is one of the three largest causes of bad bar codes.

Ratio

Width of the wide bars divided by the width of the narrow bars. This is only for two width bar codes. Violation of this rule is one of the three largest causes of bad bar codes.

Self-Checking

A single printing defect will not cause the character to be transposed into another valid one.

Two dimensional bar code

Symbology that has multiple lines or vertically different rows represent different data.

Variable length

Bar code can have as many characters as is required by data.

X

Width of the narrowest element. Violation of this rule is one of the three largest causes of bad bar codes.