Frequently asked questions about ZP4

  1. What is ZP4?
  2. How can ZP4 help me?
  3. How does ZP4 work?
  4. What are carrier route numbers?
  5. Does ZP4 print mailing labels and barcodes?
  6. Will ZP4 find duplicates in my address list?
  7. What's the best database or program for maintaining address lists?
  8. How long does it take to automatically process my address list?
  9. Do I need a fast DVD-ROM drive?
  10. How large is the ZP4 database?
  11. Can other programs directly access the ZP4 database files?
  12. Does the ZP4 database include personal names with addresses?
  13. What if my address lists contain errors?
  14. How long has ZP4 been available?
  15. Is ZP4 CASS Certified™? What is CASS™?
  16. How often is ZP4 updated?
  17. How often do I have to update the ZP4 DVD-ROM?
  18. What are DPV®, LACSLink®, SuiteLink™, DirectDPV™, eLOT®, and Geo?
  19. Can ZP4 distinguish between residence and business addresses?
  20. Can I use ZP4 on more than one computer?
  21. Can I let people access the ZP4 database on my web site?
  22. Can I include the ZP4 database in a product I am selling?
  23. Can I use ZP4 to process data for my clients or to produce data or services?
  24. What platforms does ZP4 run on?
  25. How do I order ZP4 and what does it cost?
  26. Can I download ZP4?
  27. What if I have a question not answered above?

1. What is ZP4? ZP4 is software and official United States Postal Service® data files on a single DVD-ROM that provides a powerful tool for automatically determining the correct mailing address, ZIP + 4® code, and mail carrier route number for any location in the United States.

2. How can ZP4 help me? ZP4 adds ZIP + 4 codes and mail carrier route numbers to your address files so you can qualify for bulk mail postage discounts and pay much less postage to send your mail. ZP4 will also correct and standardize addresses, so you can confirm and validate addresses, avoid undeliverable addresses, and easily find duplicates within your list.

3. How does ZP4 work? ZP4 can be used three different ways:

In batch mode, ZP4 can process a database of any size, automatically correcting and standardizing every address in the file. ZP4 can process address lists in dBase, Access, Excel, FileMaker, Oracle, SQL Server, fixed-field text, delimited text, and other file formats.

Any program can also pass addresses directly to ZP4 in memory, and ZP4 will pass the corrected and standardized address records back to the program, so any database or application can be given built-in interactive address correction capabilities. The ZP4 disc includes templates and demo programs with source code showing how to send and receive address records from a variety of popular programming environments, including C, C#, Delphi, and Visual Basic.

ZP4 also provides an excellent user interface. To manually find an individual address, just type in a name to make ZP4 instantly find a city or street. Or, click on a state listed in ZP4's first window, and ZP4 immediately displays all the state's cities in an adjacent window. Click on a city, and ZP4 instantly lists every street in that city. Click on a street, and ZP4 displays the house number ranges, apartment number ranges, ZIP + 4 codes, and carrier route numbers for that street.

4. What are carrier route numbers? Carrier route numbers identify the route each mail carrier follows when delivering mail. Using carrier route numbers allows you to send mail at rates even lower than barcoded ZIP + 4 rates, although you must have ten or more pieces to the same carrier route number for the pieces to qualify for that rate.

5. Does ZP4 print mailing labels and barcodes? Yes, ZP4 includes the necessary software for sorting and printing barcoded First Class Automation letters and postcards or Standard Automation letters, including the generation of the required forms and reports so your mail qualifies for certain bulk mail discounts. The ZP4 DVD-ROM also includes barcode fonts that can be used by any database or application program to print a postal barcode. Once ZP4 has coded an address, a postal barcode can be output by any program by using the barcode font.

6. Will ZP4 find duplicates in my address list? The ZP4 DVD-ROM includes "duplicate detector" tools for finding and marking or deleting duplicates within an address list. Note that once you use ZP4 to scrub your address list, non-standard addresses are automatically converted to the same form (for example, BOX 1, P.O. Box 1, and Post Ofc Box 1 all become the preferred PO BOX 1), and just about any database can then easily find duplicates.

7. What's the best database or program for maintaining address lists? Our customers use many, many different brands of software for maintaining their address lists, and each customer has different reasons for preferring the system they use. ZP4 is designed to be a convenient address correction tool regardless of where an address list is actually stored.

8. How long does it take to automatically process my address list? Processing speed will vary with your hardware configuration, and mostly depends on the type of disk drive where the ZP4 database is located. Also, the more RAM you have, the more ZP4 will be able to cache results in memory and avoid disk reads, thereby speeding up processing even more. Fast machines, reading the ZP4 database from a hard disk or solid state disk and tuned to minimize disk reads, have been clocked at many millions of records per hour.

Processing time can vary greatly, depending on how geographically dispersed your addresses are from each other and how much address correction ZP4 has to do. Once an address list is corrected and standardized by ZP4, subsequent processing of the same list will be much faster. In general, users with larger lists have faster computers, and speed is never an issue. ZP4 also includes a time limit option allowing you to specify the maximum number of milliseconds you're willing to wait for any address record to be scrubbed.

9. Do I need a fast DVD-ROM drive? No, because ZP4 is installed on a writeable disk, such as a hard disk or solid state disk.

10. How large is the ZP4 database? As of July 2013, the approximate size of the ZIP + 4 database is 710 megabytes. The extra optional databases use approximately: 1.3 gigabytes for DPV, 376 megabytes for LACSLink, 516 megabytes for SuiteLink, 177 megabytes for CRC, 39 megabytes for DirectDPV, 735 megabytes for ELOT, 25 megabytes for RDI™, and 2.1 gigabytes (fast version) or 900 megabytes (slow version) for GEO.

11. Can other programs directly access the ZP4 database files? For distribution purposes, ZP4 keeps most of its database partially compressed in a proprietary format accessible by the ZP4 application program. However, ZP4 can export any city, state, or ZIP Code range of the ZIP + 4 database to an uncompressed tab-separated text file, if you want to directly manipulate the data yourself. (DPV, LACSLink, SuiteLink, RDI, and DirectDPV databases are kept encrypted by the Postal Service™ and aren't exportable.) There's lots of data, and searching it can be extremely complicated because of the way the Postal Service organizes address records. It's usually easiest to let the ZP4 application do the job of searching for an address. Your custom applications can also access arbitrary ZIP + 4 database records through ZP4's programming interfaces.

12. Does the ZP4 database include personal names with addresses? No. ZP4 is not a list of addresses, but a tool to correct existing lists of mailing addresses. Many individual addresses are listed in the ZP4 database, but most of the records identify groups of low and high house numbers, or low and high apartment numbers, because if an address is within a given range, the corresponding ZIP + 4 code can then be determined. Individual building addresses are usually identified when the building contains apartments or commercial suites. Personal names are never identified. However, ZP4 does list individual addresses, including company names, for organizations that have been assigned unique ZIP + 4 codes by the Postal Service. The DPV database can verify specific mailing addresses, but is encrypted by the Postal Service to prevent using DPV as an address list.

If you're trying to acquire a list of addresses, search the Internet for vendors who sell address lists and mailing lists. Once you have a list of addresses, you can use ZP4 to validate, scrub, and standardize your list.

13. What if my address lists contain errors? ZP4 will detect all address errors and automatically correct most of them, including spelling errors and dozens of other kinds of errors. For any address that can't be automatically corrected, ZP4 will assign applicable error codes, which can be saved in the database you're updating.

14. How long has ZP4 been available? The first version of ZP4 began shipping in 1990. ZP4 superseded carrier route and five-digit ZIP® databases, which shipped in 1989, when Semaphore became a licensee of the Postal Service. Semaphore Corporation was founded in January 1982.

15. Is ZP4 CASS Certified? What is CASS? Yes, ZP4 is CASS Certified, and has been regularly recertified, ever since CASS regulations became mandatory in 1991.

CASS is the Postal Service certification program designed to improve the accuracy of ZIP + 4 codes, five-digit ZIP codes, and carrier route codes that appear on addresses. (Postal Service advertising guidelines do not allow vendors to reveal how the acronym "CASS" was derived, although the original phrase is still used in Domestic Mail Manual 708.3.1 and numerous other Postal Service documents.)

CASS Certified software are programs like ZP4 that have been tested and certified by the Postal Service CASS department as meeting their minimum requirements for "scrubbing", correcting, and validating address lists. CASS certification consists of a test administered annually: a large list of addresses of various types from around the country are selected by the Postal Service. The addresses may or may not have correct data fields (address, city, state, ZIP, and so on). The software product being certified must match the address list to the ZIP + 4, DPV, LACSLink, and SuiteLink databases, and correct and standardize the various data fields. The corrected address list is then submitted to the Postal Service for scoring.

The Postal Service computes what percentage of the software's standardized output addresses are correct. To become CASS Certified, software must achieve a 98.5% or higher match rate for ZIP + 4 codes and carrier route numbers, and 100% for delivery point barcode extension numbers. (Although these percentages sound high, most addresses in a CASS test are easier to correct than typical addresses found in real mailing lists. For that reason, ZP4 also recognizes and corrects numerous additional common errors found in typical address lists, but not found in the CASS test and not properly corrected by other brands of "certified" software.)

Nowadays, the Postal Service considers the phrase CASS Certified addresses improper usage, and that people should instead say CASS processed addresses when discussing a list that has been corrected and standardized with CASS Certified software (because it's the software that's certified, and the list is then processed by the certified software). However, "CASS Certified addresses" has been widely used in the industry since long before the Postal Service began making the distinction, so it is now essentially a generic term.

ZP4 (with DPV, LACSLink, and SuiteLink installed) can automatically fill out and print CASS postal form 3553 when processing an address list, to document that your list has been processed with CASS Certified software. Form 3553 is required when obtaining certain bulk mail postage discounts.

16. How often is ZP4 updated? New editions of the ZP4 database are built from Postal Service files and issued every month, so customers can use the latest available data. The Postal Service maintains and updates the master copies of their postal databases, which continuously undergo surprisingly large numbers of additions, changes, and deletions. Using ZP4 for postal discounts, or for access by multiple employees, is prohibited after the database bimonthly expiration date. A single ZP4 user may use an expired database for address processing that doesn't require CASS form 3553, although the database will be considered obsolete and certain outputs can't be generated with an expired database.

17. How often do I have to update the ZP4 DVD-ROM? You only have to purchase a current unexpired ZP4 disc if you want to generate CASS form 3553 or if you require multi-employee access. Since any monthly ZP4 DVD-ROM edition actually expires after two months, purchasing only six editions per year (every other month) allows unlimited CASS form generation and continuous multi-employee access, year round. However, with careful planning, many mailers can update ZP4 even less frequently. That's because once an address list is processed by ZP4, that particular list will qualify for ZIP + 4 postage discounts for 180 days (or for carrier route discounts for 90 days) before having to be reprocessed, but only if you freeze your address list and don't add, change, or delete any records.

In theory, you can use a current ZP4 DVD-ROM, clean your list, print a CASS form, and mail for 180 days (or 90 days if using carrier routes) using the same CASS form for each mailing before you have to reprocess your list with ZP4 again, as long as you don't change any records in your list. In reality, you'll probably constantly add, change, and delete records (which obsoletes the CASS form), so you typically need to reclean and reprocess before each mailing in order to generate an accurate CASS form. At the time you clean and process your list, you must use an unexpired edition of the ZIP + 4 database.

A new database is available every month, but is considered expired by the Postal Service after two months, so you need to use a ZP4 DVD-ROM that covers the two-month period in which you clean your list and print a CASS form. Using a database to assign ZIP + 4 codes or carrier route numbers for postal discounts is prohibited after a database expires. DPV, LACSLink, SuiteLink, and eLOT outputs can't be generated with an expired disc edition. DirectDPV, RDI, and Geo outputs expire 30 days before the ZIP+4 database.

18. What are DPV, LACSLink, SuiteLink, DirectDPV, eLOT, and Geo? DPV is a Postal Service database included on the ZP4 DVD-ROM and used to enhance address validation. Without DPV, ZP4 can only determine a candidate ZIP + 4 code for an address. With DPV, ZP4 can also determine whether the address is a valid location where mail is actually delivered. ZP4 is the first product ever certified by the Postal Service for DPV processing.

LACSLink is the Postal Service database that allows ZP4 to automatically perform conversions from one address style to another, typically from a rural-style box number to a street name (for example, RR 1 BOX 127A is converted to 17255 SCENIC RD). House and Post Office box renumbering and street renaming are also handled by LACSLink.

SuiteLink is the Postal Service database that allows ZP4 to add secondary (suite) address information to business addresses.

DPV, LACSLink, and SuiteLink (not just the ZIP + 4 database) must all be used to determine the proper CASS generated ZIP + 4 code for an address.

DirectDPV is the Postal Service database that lets ZP4 perform fast lookups of barcode numbers, thereby skipping ZIP + 4 database searches when reprocessing a previously CASS-processed address list. As a result, updating lists with DirectDPV allows standardizing and revalidating addresses at very high speeds. ZP4 is the first product ever certified by the Postal Service for DirectDPV processing. DirectDPV expires monthly.

eLOT is a Postal Service database that allows ZP4 to automatically find line of travel numbers so mail qualifies for certain presort discounts.

Geo allows ZP4 to automatically determine the latitude and longitude, and Census Bureau tract and block numbers, for ZIP + 4 codes. Geo expires monthly.

19. Can ZP4 distinguish between residence and business addresses? Yes. ZP4 includes the RDI database for determining if an address is a residence or a business. The RDI database expires monthly.

20. Can I use ZP4 on more than one computer? The database from a single ZP4 DVD-ROM can only be installed and used on one computer. However, until the database expires, any number of employees can process addresses against that single copy of the database over a network. That means you can provide unlimited address scrubbing for any number of employees sharing one installed database by simply updating the database every two months.

The ZP4 database itself, or extracted portions thereof, may be moved from machine to machine, but you are not allowed to maintain multiple copies of the same data for simultaneous use on multiple disks or by multiple employees. Instead, you must purchase additional original master data discs for each employee if you cannot share one copy of the data. Multi-employee access always requires the current, unexpired database.

21. Can I let people access the ZP4 database on my web site? Yes, if the site is restricted to your employees, and you're using the current, unexpired database. No, if your web site is providing access to the database or ZP4 results to anyone outside of your company, or if the database has expired. Only the company or organization that purchased the database may use ZP4, and the current unexpired database is required for multi-employee access. Using ZP4 to scrub incoming addresses captured at a web site (such as during order entry) is allowed, if scrubbing is accomplished without granting your customers (or the public) access to arbitrary use of the ZP4 database (such as scrubbing multiple addresses, or returning ZP4 "answers" to the web browser).

22. Can I include the ZP4 database in a product I am selling? No, but you can make your product call ZP4's interfaces. If your customers then install the ZP4 database after purchasing a ZP4 DVD-ROM from you or from Semaphore Corporation, your product will automatically offer complete address scrubbing capabilities to your customers. Note that ZP4 discs are sold only at retail, and ZP4's standard license and restrictions on use apply to all ZP4 end users.

23. Can I use ZP4 to process data for my clients or to produce data or services? No, that's prohibited by ZP4's license.

24. What platforms does ZP4 run on? Windows. The only hardware requirement is a local or networked DVD-ROM drive for installation.

25. How do I order ZP4 and what does it cost? Each ZP4 DVD-ROM is $99 plus shipping, shipped prepaid from Semaphore Corporation. Shipments to California destinations are taxable. A single ZP4 disc contains all ZP4 software and data for the entire United States. See our online order options for more details.

26. Can I download ZP4? No, the product is distributed only on DVD-ROM.

27. What if I have a question not answered above? First check the support page, otherwise contact Semaphore Corporation.


Go to the ZP4 home page.
Semaphore Corporation is a non-exclusive licensee of the United States Postal Service. The prices of Semaphore Corporation products are not established, controlled or approved by the Postal Service. The following trademarks are owned by the United States Postal Service: CASS, CASS Certified, DirectDPV, DPV, eLOT, LACSLink, RDI, SuiteLink, ZIP, ZIP Code, ZIP + 4, Postal Service, and United States Postal Service. [DA#4.07]