USPS OneCode 4-State Customer Barcode
USPS Intelligent Mail (aka: OneCode) is a height-modulated
4-state barcode type used in the USA. It allows both PLANET and POSTNET
barcode information to be combined into a single barcode to track mailings,
request address-quality services (including updated address-change information)
and return-mail service.
Intelligent Mail Barcode Index:
OneCode are the USPS implementations of the 4-State Customer Barcode
type. Other implementations of the 4-State Customer Barcode exist in
other countries such as
is used for automated mail sorting and addressing in the UK.