As a final note, GAO recently surveyed six business associations whose members mail large volumes of first class mail. Although not a representative sample, GAO found that while there is some interest in ZIP+4, businesses are still concerned about the cost of converting their address files (even with the current rate incentives) and whether the USPS presort program (and discounts) will end as a result of ZIP+4. In order to promote conversion, USPS is allowing "comingling" or mixing of up to 15 percent non-ZIP+4 mail in a ZIP+4 presort first class mailing until February 1, 1985, and up to 10 percent until October 1, 1985. As yet, however, there is little evidence that business mailers are giving ZIP+4 conversion a high priority.
Multi-line OCR performance. A major advantage of multi-line OCRs is the ability to read, code, and sort 5-digit ZIP mail to the 9-digit level. That is, unlike the single- line OCR, the multi-line OCR can process a significant percentage of 5-digit ZIP mail as if the ZIP+4 were being used but without actually requiring the ZIP+4 code to be on each letter. The multi-line OCR does this by matching the multi-line address information on the envelope with address and ZIP+4 information stored in a computerized address directory. Even though there is no ZIP+4 code on the envelope, when a match is made,
the multi-line OCR prints the 9-digit barcode on the envelope.
At issue is not whether but how well the multi-line OCR can process 5-digit mail to the 9-digit level. USPS has estimated that the multi-line OCR can process 60 percent of 5-digit mail accepted by the OCR to the 9-digit level extra based on acceptance tests of the REI equipment. However, USPS notes that the 60 percent is "a projection that was not fully tested.” Based on the 60 percent multi-line performance estimate (5-digit to 9- digit level) and more complete data available on single- and multi-line OCR processing of 9-digit (ZIP+4) mail, USPS developed a set of curves shown in figure 8 as alternatives A,