VERIFIED SOLUTION i

How to locate the Postage rates in MailStream Plus

MSP = MailStream Plus
PRF = MSP monthly Postal Reference Files
PO! = PostalOne!

After installing the March or April PRF files, an MSP job was using the new April 10 rates on the MSP Postage Statement.  But when the Mail.dat files were uploaded to PO!, the PO! Postage Statement using the old pre-April 10 rates?

The reason-

MSP uses the dollars/cents rates that are actually in the PRF files.  

PO! reads the Mail.dat files.  The Mail.dat files do not contain dollars/cents rates.  The Mail.dat files contain information such as the mail class, type of mail piece, mail piece weight, and the rate category it was presorted into.  By looking at all of the information, PO! determines on-the-fly the actual dollars/cents postage for each mail piece. 

Also in the Mail.dat files are induction date fields populated by using xx INF parameters in the MSP job, such as MDMFSS, M3DATE, MDMFDD, MDMFSD.  By looking at those dates, PO! knows when the mailing is going to be dropped at the USPS entry facility.  
In the case of the April 10 2016 rate changes, PO! could tell by the induction date when the mail will be dropped, and then know whether to use the pre-April 10, or the April 10 and later, rates.

In the job that raised this issue, the MSP job had xx INF parameters indicating the mailing was going to be dropped prior to April 10, so PO! used the old rates.  But since the March or April PRF files were being used in MSP, MSP was using the new rates.
UPDATED:  August 8, 2017