United States Postal Service

For a thorough description and high-level references about the USPS ZIP code system, see here.

Contents

  1. United States Postal Service
    1. History
    2. Mailing
      1. DPV
      2. LACSLink
      3. SuiteLink
      4. eLOT
      5. RDI
      6. CASS
      7. NCOA
      8. Secure Destruction

History

Mailing

DPV

Delivery Point Validation (DPV) is a technology that determines if an address is deliverable based on the ZIP+4 code. Automated mail (a class of mail for purposes of postage) is required to pass DPV.

Locatable Address Conversion System Link (LACSLink) is a dataset that maps physical addresses, such as those often used in rural localities, to a more-standard ("city-style") address. This dataset is built from data collected during the implementation of a local 911 system.

!SuiteLink is a dataset of high-rise suite records. The intent of this product is to insert secondary designators (i.e. suite numbers) for business addresses. Using this dataset is dependent on each address having a ZIP+4 code.

eLOT

Enhanced Line of Travel (eLOT) is a technology that inserts carrier route information for an address, including delivery sequence number. By pre-sorting mail, mailers can qualify for discounted postage. It depends on each address having a ZIP+4 code.

RDI

RDI is a technology that classifies an address as being either residential or business. Note that this component alone is optional for CASS (see below). The primary intent is to better ascertain the shipping rate for an address, so that mailers can shop for alternative services.

CASS

Coding Accuracy Support System (CASS) is a certification for technologies, but the technologies themselves are often referred to as CASS as well.

A CASS-certified technology must pass a test suite by ingesting a static dataset of addresses, and then producing mailability codes and (if mailable) a new address for each record. Essentially these systems:

  1. insert the ZIP+4 and carrier route to an address
  2. run the address through all of the above technologies

NCOA

National Change of Address (NCOA) is a data system that aggregates change of address requests. NCOALink is a dataset that provides permanent replacement addresses based on that system.

A piece of mail that is undeliverable is called a nixie. The NCOA data system assigns nixie codes to addresses with a known deliverability quality. In some cases it indicates that a new address is available in NCOA, and the mail is forwarded. In other cases it indicates that the forwarding order has expired, and therefore mail cannot be delivered. (It would then be returned to sender, unless the mailer has purchased Secure Destruction service.)

Secure Destruction

Secure Destruction is a service for mailers that securely and permanently destroys mail pieces if they cannot be delivered, rather than being returned to sender. This service reduces work all around (i.e. USPS does not carry mail back to sender, USPS nixie clerks can operate in a centralized office rather than close to the mailer, mailer does not receive and process undelivered mail pieces, and so on) and reduces risk of theft of (or inadvertent disclosure by way of) intercepted, sensitive mail pieces.

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