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How to know in addition to the monthly DB files, what else can make a job's presort change between one run and the next time a job is ran using MailStream Plus

Products affected:  MailStream Plus, All versions

Operating System: All Platforms
Using MailStream Plus (MSP), mailings can be different from run to run for many reasons, but that does not mean one is right and the other is wrong.
 
1 - Of course, the monthly Postal Reference Files (PRF) database files being used can change a presort, because they use USPS data, which includes how the USPS wants the mail to be presorted and grouped together, and where the trays/sacks/pallets are to be labelled to, etc. 
Just for example, one month the USPS may want ZIP Codes 12345 and 12346 to be grouped together into the same container, and the next month they may not, or vice versa. 
And with the USPS closing/changing Facilities, for example, mail that was going to a specific facility one month, say an SCF, may be going to a different SCF the next month and that can change the presort.
 
But some other less-obvious things can change a presort too.
 
2 - The values on the P ATTR parameters-
If the weight, thickness, length, height, or volume changes, that can affect the presort, as far as how much mail will fit into a tray/sack/pallet, and that can change a presort.  For example, a slight increase (or decrease) in thickness of a letter may cause a different number of pieces to fit into a tray, and now those pieces have to be presorted into another tray.
One piece being moved can trickle down and make significant changes to a presort.
 
3 - Input records being added or removed-
In the same manner, if a record(s) is added or removed, or has a ZIP Code changed, that can affect grouping and the tray/sack/pallet preparation.
 
4 - The version of MSP-
The USPS makes presort changes once or twice a year, which can revise the presort rules as-to how the USPS wants the mailing to be presorted.  Also, MSP has changes or fixes in the Releases and Updates, which can change a presort.
 
5 - The Piece ID Code itself on P ATTR parameters-
Say a mailing has P ATTRs with codes A, B, and C.  In the next run, the B code gets changed to D but all the piece values stay the same.  That affects the order of the pieces in MSP's internal work-stat records.  Those records are what MSP looks at in doing the presort, and if they are in a different order, then different pieces may be put into groups which affects how the presort turns out.
 
6 - Another vendors software being used to do a presort for comparison-
Sometimes users compare MSP results to another vendor's presort application's results, and question the differences.  Although they both presort according to the same USPS Domestic Mail Manual (DMM), the regulations do allow leeway.  There are places where certain levels of presort are optional, and one software application may do it and the other may not.  And in some cases the USPS allows the mailer (or the software application) to decide how thick to make bundles, or how much weight to put on a pallet, etc.  And many many other things are possible to be different within the DMM regulations, while both presorts are 'legal' and acceptable to the USPS.

7) - Many parameters can/will affect the presort-

For example-
Using ALG LV and changing the size of trays or sacks being used, or the destination levels of trays/sacks to be made. 
Using ALG CR and changing the type Carrier Route presort.
Using xx FRC, xx MIN, or xx MAX (xx being the first two bytes to indicate pallets, bundles, etc) to change thickness, weights, etc.
UPDATED:  October 3, 2017