Intelligent Mail® Barcode (IMb) 4-State Specification
This document provides the specifications for generating and printing the Intelligent Mail® barcode (IMb) used in the U.S. Postal Service (USPS) mailstream. The IMb is also known as the USPS OneCode Solution or USPS 4-State Customer Barcode (abbreviated 4CB, 4-CB, or USPS4CB). This document provides information for software developers and users alike on the creation and printing of compliant IMb. It describes the symbology, format, fields, values and other characteristics of the Postal Service IMb.