VERIFIED SOLUTION i

Resolve when you pass a locale key into MailStream Plus (MSP) using DRPKEY/PLTKEY parameter MSP drops off the first byte

The Locale key from the USPS is 7 bytes.  When you pass a locale key into MailStream Plus (MSP) using DRPKEY/PLTKEY parameter, MSP drops off the first byte, and then puts ‘LOC’ and the remaining 6 bytes into the CSM 9 byte field.  The parameter- 
EP INF     X               DRPKEY  PW1A588
posts:
LOCW1A588
to the CSM-1167 - Entry Point - Actual / Delivery - Locale Key
 
Is this correct?
 
Yes, the USPS changes the first byte of the locale code when they want or need to.  The rules for populating CSM -1167 is to drop the first byte, then put 'LOC'   and the remaining 6 bytes.
The first byte value is not needed in CSM-1167.
 
UPDATED:  April 21, 2017