DPV & LACSLink® Locking

DPV and LACSLink include USPS-mandated false-positive protection. If a seeded false-positive address is processed, the engine locks until the address is reported and an unlock code is applied.

What locking is

To protect the integrity of DPV and LACSLink data, the USPS seeds it with false-positive addresses. Processing one of these addresses causes the engine to lock, and the USPS requires the offending address to be reported before processing can continue. This is expected, standard behavior for any CASS-certified engine — your integration should be prepared to detect and handle it.

Encountering a lock

When a record triggers a lock, the job finishes with an error indicating that a DPV or LACSLink lock occurred. If you try to start the engine again while the lock is still in place, it will refuse to start and report the existing lock.

The engine writes two files to the log directory when a lock occurs:

  • A log file (for example, DPV_LOCK00.log or LACS_LOCK00.log) describing the lock event. This file must not be modified in any way.
  • A lock-code file (for example, DPV_LOCK_CODE.dat or LACS_LOCK_CODE.dat) containing a unique code used to generate the unlock code.

Resolving a lock

Resolving a lock means reporting the false-positive record to Firstlogic (who report it to the USPS) and applying the unlock code you receive in return. The process is:

  1. Report the lock — send the lock log and lock-code files to Firstlogic's DPV/LACSLink false-positive reporting address, following the current instructions in your product documentation and support materials.
  2. Receive an updated lock-code file — Firstlogic returns an updated file containing the unlock code.
  3. Remove the offending record — the lock log identifies the record that triggered the event; remove it from your input so it doesn't lock again on the next run.
  4. Apply the unlock code — with your application stopped and the files closed, replace the original lock-code file with the updated one and resume processing. The engine reads the unlock code, clears the lock, and removes the lock files automatically.
Important: Don't edit the lock files, and make sure they aren't open in an editor when you resume — the engine needs exclusive access to complete the unlock.
Note: The specific reporting address and turnaround are governed by USPS requirements and can change; always follow the current instructions from Firstlogic support rather than a hard-coded contact.
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