UPC-E

UPC-E is a variant of the UPC (Universal Product Code), more compact than the more-common UPC-A. It is only able to encode a subset of the codes used in UPCs, being limited to ranges of code numbers that have sections which can be omitted (e.g., extra zeroes). There are apparently also UPC-B, UPC-C, and UPC-D versions as well, but they are not often mentioned and may not be in current use.

An optional additional bar code to the right of the UPC bar code encodes a supplemental 2 or 5 digits, used primarily on books and magazines. On magazines this encodes the issue number (the main bar code only encodes the periodical series) allowing issue-by-issue inventory tracking, while books use a supplemental code to indicate the suggested retail price.

Specs

 * UPC-E specification

Software

 * Review of barcode scanner apps
 * iOS app to read UPC/EAN codes and find product info/prices
 * Android app to read UPC and QR codes to look up product info/prices and other info coded or linked in bar codes
 * Bar Code app (iOS)
 * barcode.php

Developer libraries and modules

 * ZBar bar code reader library: cross-platform
 * zxing (Zebra Crossing) (barcode library for Java, ported to some other systems)
 * MediaWiki extension to generate UPC, EAN, and Code39 codes

Utilities

 * Global UPC database
 * Another UPC search site
 * UPC-E bar code generator
 * Online barcode generator (supports many different formats)