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MailStream Plus - what are the minimum quantities for making First-Class Flats bundles and trays

MailStream Plus™, all versions, all platforms
For a First-Class mailings you need 500 pieces minimum.  The full eligibility requirements are in DMM 233.

First-Class Flats go into Flats Trays.
First-Class Non-Auto Flats are prepared per DMM 235 7.0
First-Class Auto Flats are prepared per DMM 235 8.0

There is no minimum quantity per bundle or per tray.  The reason is- imagine a mailing that has of 499 pieces to a 5-digit ZIP Code that fit into 4 trays, and 1 piece to another 5 digit ZIP Code.  That 1 piece *has* to go somewhere.
What will happen is that the 4 trays will be made with the 499 pieces to the 5-digit destination.
And then a final MADC bundle will be made with the 1 piece, and a MADC Tray will be made with that 1 piece.

The Audit Trail preparation might look like this-
                      Destination   Copies  Bundle                                                                     Cumulative

     PS F-Tr 1        00902 5DG        125  5DG...........63  5DG...........62                                                125
     PS F-Tr 2        00902 5DG        125  5DG...........63  5DG...........62                                                250
     PS F-Tr 3        00902 5DG        125  5DG...........63  5DG...........62                                                375
     PS F-Tr 4        00902 5DG        124  5DG...........62  5DG...........62                                                499
    Sack/Tray Presort Total            499  4 Trays, 8 Bdls, 499 Pcs, 29.94 Lbs, 0.7277 Cu Ft, 3.7425 Ft

     RS F-Tr 5        208   MADC         1  208 MADC.......1                                                                  500


The USPS looks at the preparation another way, saying when you *have* to make a bundle or tray to a destination. The rules in general are that if you have 10 pieces (minimum) to the same destination, then you have to make a bundle.  
And then if you have a full tray to a destination, you have to make the tray.  And in many or most cases you cannot make the  tray unless it is legally full.

For First-Class Automation Flats, the above is from DMM 235.8.5.  There is also another type of Auto Flats preparation that does not use bundling in DMM 235.8.6.

(The DMM references above are as-of May 2019)
UPDATED:  May 16, 2019