postal-logistics

POSTNET / PLANET (Legacy US Postal) (POSTNET)

Historic 2-of-5 height-modulated linear symbology formerly used by USPS to encode 5, 9, or 11-digit ZIP codes for automated mail sorting (retained for legacy archive systems).

Governing Specification: USPS Publication 25 / Legacy Postal Standard

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Data Format & Required Fields

Encodes numeric ZIP digits where each digit is represented by 5 bars (2 tall, 3 short) with Modulo 10 check digit and start/stop frame bars.

Allowed Character Set5, 9, or 11 numeric digits (ZIP, ZIP+4, or Delivery Point).

Payload Length Rule Between 5 and 11 characters

Check Digit / Checksum Rule Requires a verified modulo-10 check digit to prevent scanner misreads and data transposition errors.

Example Valid Format12345678901

Industry Guidance & Practical Applications

Legacy postal archive systems and historical document verification
Retrofit envelope printing equipment compatibility
Archival mail trace verification

Packaging & Scanning Notes: Officially superseded by IMb in 2013, but still supported for enterprise archive retrieval.

Symbol Constraints & Label Guidelines

Legacy format largely replaced by USPS Intelligent Mail Barcode (IMb).
Purely numeric; encodes ZIP codes only.