Intelligent Mail
Four bar heights, rather than the two of POSTNET, allow the Intelligent Mail barcode to pack a 31-digit data string into 65 bars: each bar independently occupies an ascender, a descender, both, or neither. The United States Postal Service adopted it in 2009, consolidating the routing function of POSTNET and the tracking function of PLANET into a single symbol. The encoded string carries a barcode identifier, a service type code, a mailer identifier, a serial number, and a routing code, so one mailpiece can be tracked through the network as well as sorted. Bars stand 3.68 mm tall at a 0.38 mm X-dimension. The symbology is numeric, fixed in length, and outside the GS1 system.
The current USPS mail barcode that replaced POSTNET and PLANET, encoding both routing and tracking information in a single 65-bar symbol. Intelligent Mail uses four bar heights to encode a 31-digit data string that includes barcode ID, service type, mailer ID, serial number, and routing code.