Intelligent Mail Barcode - also known as: USPS OneCode 4-State Customer Barcode, OneCode 4CB, USPS 4CB, 4-CB, 4-State Customer Barcode, USPS OneCode Solution Barcode. (01234567094987654321-01234567891) Accepts: Up to 31 digits (required 20-digit Tracking Code, and up to 11-digit Routing Code; this may be 0, 5, 9, or 11 digits). If the Routing code is included, it should be spearated by a hyphen - like this example. For other types of barcodes visit our Barcode generator.