How do you put 'Flats' mail pieces into trays with MailStream Plus

Product Affected:  MailStream Plus™
The USPS Domestic Mail Manual (DMM) regulations allows putting Flats into trays for certain types of mailings.   MailStream Plus (MSP) supports this.  
For other types of mailings it is not allowed, and MSP will not do it. 

For further information, the DMM is available at

Except for First-Class Flats, by default Flats will go into sacks.  Use the ALG LV parameter positions 14 and 16 to indicate that you want a certain type of tray to be used instead of sacks (when allowed).

Further information on using the ALG LV (and other MSP parameters) can be found in the MailStream Plus Guide.

In some cases, using trays is only allowed when palletizing.  It is best to refer to the DMM, or verify with the USPS that trays can be used for a specific mailing, prior to presorting/preparing the mailing.
UPDATED:  October 1, 2018