VERIFIED SOLUTION i

Posting the actual P ATTR Identifier codes into Mail.dat MPU-1003 (Mail Piece Unit ID) in MailStream Plus


 
Regardless of the actual P ATTR Identifier codes, by default MailStream Plus (MSP) uses sequential numbers for MPU-1003 (Mail Piece Unit ID), such as 00001, 00002, etc.

But on the REPORT MAILDAT position 44, there is an option 'F' to use the actual P ATTR codes.  
Note: since MPU-1003 is only 5 bytes long, if the P ATTR codes are longer than 5-bytes, then sequential numbers will be used instead.
UPDATED:  August 31, 2018