Without DirectDPV, standardizing and validating an address requires performing a full CASS matching attempt: the ZP4 address correction engine is required to consider all candidate city records, then consider all candidate street records within each candidate city, then consider all candidate address records within each street, then finally select the "best" match. Even if an address has already been processed with CASS Certified™ software, reprocessing the address with a subsequent database edition requires that the complete matching procedure be repeated, which can require a signficant and unpredictable number of probes and reads in the ZIP + 4® database.
To process an address, DirectDPV required the record had already been CASS processed and delivery point validated (or previously processed with DirectDPV) to generate a barcode number. Using DirectDPV, users could bypass future CASS processing and immediately determine what address components have changed, simply by letting ZP4 perform a fast lookup of the barcode number in the DirectDPV database. DirectDPV would immediately indicate how any component (ZIP + 4, delivery point, carrier route, house number, predirectional, street name, suffix, postdirectional, unit name, apartment number) had changed since the address was previously CASS processed. As a result, updating lists with DirectDPV allowed standardizing and revalidating addresses at very high speeds.
Benchmarks show ZP4 would validate previously CASS processed address records five times faster when DirectDPV was used. (That's start-to-stop time, including all file I/O, application, and operating system overhead. A small percentage of records fed through DirectDPV would typically be marked as still requiring subsequent CASS processing, which was a required feature of DirectDPV logic.)