postalref

LACSLink

LACSLink is a secure USPS dataset of converted addresses, mostly from the 911 emergency system, which often changed rural-style addresses to city-style ones. Address-matching software looks up an old address in it and returns the new one, so a mailer can update its mailing list.

Updated October 31, 202630 sources

What it is

LACSLink is a data-only product of addresses that were converted, modified or changed by USPS or for the 911 emergency system. It also holds city-style addresses that were renamed or renumbered. The data sits in secure hash tables, so software gets a new address only by querying with the old one.

LACSLink is part of CASS, the USPS test of the quality of address-matching software. Every end user of CASS software must use LACSLink, and it is not a certification of its own. End users get LACSLink inside a CASS Certified product from a CASS manufacturer. Standalone users get a specially packaged LACSLink from a licensed service provider.

Current addresses mean fewer undeliverable and duplicate mailpieces, which lowers a mailer's costs. USPS releases LACSLink monthly through its Electronic Product Fulfillment website. Only the two most recent monthly releases are available to download.

How it works

A LACSLink lookup takes a 50-character address field, not parsed, and a 5-digit ZIP Code. Software computes a SHA-1 hash of the ZIP Code and the address, and the same hash always gives the same result. On a match, the output is a new 11-digit Delivery Point Code with a Hint Byte that turns it back into a text address.

USPS provides a street name table of the streets in the LACS database for each 5-digit ZIP Code.

Software decides whether to run a lookup from the address's match in the ZIP + 4 file.

  1. Query the ZIP + 4 file first.
  2. On a regular ZIP + 4 match with no LACS flag, skip the LACSLink lookup.
  3. On a match to a record with an L in the LACS Status Indicator, hash the address and look it up.
  4. On a rural route or highway contract default match, look it up only if the street is in the street name table.
  5. With no ZIP + 4 match, query the street name table, and look up the address when its street is there.
  6. When the street is not in the table, run a fuzzy name comparison and look up with the matched name.
  7. Skip the fuzzy comparison and the lookup for a missing rural route, highway contract or PO Box street.

When LACSLink finds a new address, CASS software should not return the L LACS indicator.

Preparing the address

The address must be standardized, but it needs no ZIP + 4 code. A change of one letter or space gives a different hash, so software cleans every address the same way.

  • A pound sign replaces the unit designator when a secondary number follows, so 123 MAIN ST APT 7 becomes 123 MAIN ST # 7.
  • Leading zeros come off primary, route and secondary numbers, and extra spaces go.
  • Rural routes, highway contracts and PO Boxes follow Publication 28, so Rural Route 1 Box 15 becomes RR 1 Box 15.
  • Words that are not part of the address go, so 1234 HILLCREST PIKE BEHIND THE CHURCH becomes 1234 HILLCREST PIKE.

Return codes

Software returns one of four return codes, or none, for each address. It should return a code only when it actually queries the llk.hsl hash table.

CodeNew addressMeaning
AYesThe input matched a record in the master file, and a new address could be furnished.
00NoThe input could not be matched to a record in the master file, so no new address could be furnished.
14NoThe input matched a record, but the new address could not be converted to a deliverable address.
92YesThe input matched a record, but the input had a secondary number the record did not, in a ZIP + 4 street or highrise match.

Getting a license

LACSLink has three license categories. Each one needs certification documents, then a signed license and payment of its fee.

LicenseWhat it allowsFee
Interface DeveloperDevelop a LACSLink interface for internal use and for third parties.$2,470.00 at first, then $710.00 a year
Interface DistributorDistribute the LACSLink interface and redistribute the LACSLink data.$2,740.00 a year for the interface and $710.00 a year for the data
End UserUse LACSLink to update addresses and mailing lists, internally and for third parties.$710.00 a year

The first license year is prorated. USPS waives the developer and distributor fees for manufacturers of CASS and NCOALink Full Service Provider software. It waives the End User fee for NCOALink Full Service Providers.

An End User licensee needs no separate certification, but USPS may audit its LACSLink process. Its interface is tested with a CASS and LACSLink Stage II test file.

A developer completes a certification package for each site that develops interface software.

  1. Submit the application, statements, key personnel listing and security documentation for USPS approval.
  2. Sign the LACSLink Software Development License Agreement that USPS sends after step 1.
  3. Pay within 10 calendar days of receiving the executed license agreement.
  4. Build the interface with the Software Developer Kit that USPS sends once payment arrives.
  5. Ask USPS in writing for a certification test, with a Software Product Information Form.
  6. Receive the software certification notice once USPS finds steps 1 to 3 complete.

Rules

When a new LACS converted address is found the new address must be returned.

CASS software must return the new address whenever LACSLink finds one.

Mailers who do not want to update their customer’s original address information when LACSLink returns an updated address may not use the ZIP + 4 code associated with the new address.

A mailer that keeps the original address may not use the ZIP + 4 code of the new address.

Any time an address encounters a match to the False Positive table, the interface must cease the LACSLink process on addresses for the specific address list.

When an address matches the False Positive table, the interface must stop LACSLink processing for that address list.

Per the License Agreement, the LACSLink Product shall not be used to facilitate creation of address lists artificially.

LACSLink must not be used to help create address lists artificially.

The interface must be reviewed, tested, and approved by the USPS prior to any actual use of the LACSLink Product for processing occurring in a production environment to ensure that all license requirements are met.

USPS must review, test and approve an interface before it processes any addresses in production.

Licensees must access the LACSLink Product using USPS-certified LACSLink software.

A licensee must reach LACSLink data only through USPS-certified LACSLink software.

USPS-supplied LACSLink updates more than 105 days old shall be destroyed using common practice for disposal of sensitive materials, such as permanent file deletion.

A licensee must destroy any LACSLink update more than 105 days old, for example by deleting the file permanently.

For mailpieces processed through MASS certified MLOCRs for the purpose of claiming automation prices, the new LACSLink address along with its corresponding 11-digit barcode is required to be sprayed on the mailpiece.

To claim automation prices on mail run through MASS certified MLOCRs, the new address and its 11-digit barcode must be sprayed on the mailpiece.

What goes wrong

The product includes a table of artificially manufactured addresses, to catch address lists that were not legitimately obtained. Software compares each retrieved 11-digit ZIP Code with the one in the header file llkhdr01.dat, and a match is a false positive.

For an end user, a false positive halts LACSLink processing on that one list, and other lists may continue. The licensee must tell the customer right away. A one-time restart code restores processing. The licensee sends USPS the affected addresses at Dsf2stop@usps.gov with the subject line LACSLink False Positive.

NCOALink Full Service Providers may keep processing after a false positive, but must notify USPS at once. Service providers on MLOCR equipment may also fax the addresses to 650-577-2500. USPS may have a licensee suspend a customer after repeated false positives. Licensees keep false positive reports for five years for USPS review.

CASS tests may include false positive records, which testers email to DSF2Stop@usps.gov with the subject line CASS Test LACSLink.

The interface stops working when its LACSLink data is more than 105 days past the product date.

A mailer that keeps an original address may still use it with only its original 5-digit ZIP Code, if the address is in the ZIP + 4 file and DPV confirms it. That address does not qualify for automation discounts.

Terms

Coding Accuracy Support SystemCASS, CASS software program, CASS certification process, Coding Accuracy Support System (CASS) certification
provides hardware and software manufacturing, service bureaus, and commercial mailers a common measure by which to test the quality of address-matching software.
ZIP + 4 Product
The ZIP + 4® Product is a base reference file that can be accessed by an application to assign the correct ZIP + 4® Code associated with a physical address.
Locatable Address Conversion System IndicatorLACS indicator, LACS Status Indicator
The LACS indicator identifies addresses in the ZIP + 4® file that may be converted to new addresses.
Delivery Point CodeDPC
2 digit Delivery Point Code that completes the 11-digit ZIP Code
Electronic Product FulfillmentEPF, Electronic Product Fulfillment (EPF) web site, Electronic Fulfillment Website
A secure web-based application managed by the National Customer Support Center in Memphis TN that is used to post and receive Address Management and Address Information System products, including ACS fulfillment files.
False Positive table
To detect conditions where address records appear to be the result of artificial manufacture, and not legitimately obtained, a table of artificially-manufactured addresses is provided as part of the product.
Delivery Point ValidationDPV, Delivery Point Validated, delivery point valid
The DPV® Product identifies whether a ZIP + 4® coded address is currently represented in the USPS® delivery file as a known address record.
Multi-line Accuracy Support SystemMASS, MULTILINE CODING ACCURACY SUPPORT SYSTEM, Multi-line Accuracy Support System (MASS) certification
The MASS™ certification is a process similar to CASS but is designed for certification for Multiline Optical Character Readers (MLOCRs), Remote Video Encoding (RVE), and encoding stations to process address information and apply an accurate delivery point barcode (DPBC).
Multi-Line Optical Character ReaderMLOCR
Equipment used by mail service providers that applies a barcode and presorts mail, enabling the mail owner to take advantage of automation discounts.
Stage II
the certification test that is required to achieve CASS certification.

Documents

User Guides

Quick Service Guides

Fact Sheets

Data Files

Contact Lists

Applications/Forms

Announcements

Contacts

  • For licensing and certification, the Licensing and Certification Department answers at 1-800-589-5766.
  • For administration and technical questions, the Move Update Support Department answers at 800-589-5766 or ncoalink@usps.gov.
  • Certification materials go to the National Customer Support Center, 225 N Humphreys Blvd Ste 501, Memphis TN 38188-1001, or by fax to 650-577-5773.

Sources