Eleven digits, then bars
The Postal Service defines a delivery point code as "the finest depth of code to which a mail piece can be sorted by its address. It is usually the 11-digit numeric code formed from the ZIP+4 code and represented by the delivery point barcode (DPBC)", per the Address Information System Products Technical Guide on postalpro.usps.com, checked 2026-07-28. Nine of those digits are the ZIP and its add-on; the last two narrow it to a single point on a carrier route. Publication 28 section 226 adds the obvious requirement that a preprinted barcode must be correct for the address, city, state and code printed beside it.
The Intelligent Mail barcode swallowed it
The Domestic Mail Manual describes an Intelligent Mail barcode as one that "consists of 65 vertical bars, each representing one of four possible states: full bar, ascender, tracker, and descender", per DMM 204 at pe.usps.com, checked 2026-07-28. The Postal Service instruction sheet breaks the contents into a 20-digit tracking code field carrying the Barcode Identifier, Service Type Identifier, Mailer Identifier and Serial Number, plus a routing code field of up to eleven digits which "can contain a 5-digit ZIP Code, 9-digit ZIP+4 code, or 11-digit delivery-point code", per about.usps.com, checked 2026-07-28. Mailers may leave the routing code empty and use the barcode purely for tracking.
What a parcel carries instead
Packages use a different symbol. The manual defines the Intelligent Mail package barcode as "the USPS-developed barcode that can be read by automated parcel-processing equipment and scanning devices and consists of a data string that generally follows the GS1-128 specification", and requires it on all commercial packages. Address quality still shows up in the rules: the compliance category for address quality checks "for a timely address that validates to a unique 11-Digit DPV", with a threshold of 90, per DMM 204 at pe.usps.com, checked 2026-07-28. None of this is a knob a shipper turns. Buy a label and the right barcodes are generated with it.