VERIFIED SOLUTION i

MailStream Plus appeared to make Periodicals Automation bundles in Flats Trays thicker than what was specified on the BL MAX parameter?

Using the BL MAX parameter positions 30-34, a job had specified the maximum bundle thickness to be 4 inches.  The job was putting Periodicals Flats into Flats Trays. 

The Audit Trail had these two Trays for example, #220 and #221-

     CR F-Tr 220      301   M3D         24  30117 C008.....6  30144 C019.....9  30165 C011.....9
    Sack/Tray Carrier Total             24  1 Tray, 3 Bdls, 24 Pcs, 15.948 Lbs, 0.50254 Cu Ft, 0.8066 Ft

     PS F-Tr 221      30342 FSS         24  24 Pcs, 15.948 Lbs, 0.50254 Cu Ft, 0.8066 Ft

     
Tray 220 has three bundles in it to three different Carrier Routes, bundles of 6, 9, and 9 pieces.
     
Tray 221 might appear to have a single bundle of 24 pieces, and the mailpiece's thickness was such that a bundle of 24 pieces would be 9 inches.  
But in fact, Tray 221 was unbundled mail.  
First the Audit Trail above does not show any bundling in Tray 221.  
And looking in the output Name-Address file, the posted bundles numbers for the records in tray 221 was 000000000 for all records, indicating no bundling.  Where-as the records in the previous tray 220 had bundle numbers of 000000001, 000000002, and 000000003.

Per the DMM (Domestic Mail Manual) at pe.usps.gov-
207 25.0  Preparing Flat-Size Barcoded (Automation) Periodicals
207 25.5  Optional Tray Preparation—Flat-Size Barcoded Pieces
As an option, mailers may place machinable flats (under 201.6.0) in flats trays (see 24.0) that would normally be placed in sacks.  Mailers must group together all pieces for each 5-digit scheme, 5-digit, 3-digit scheme, 3-digit, SCF, and ADC destination.  Bundling is not permitted unless it achieves a finer presort than the presort destination of the tray. 

(The DMM references given are as-of the current DMM July 2015)

So if all of the Auto pieces in the tray are to the same destination, such as to Tray 221's destination FSS 30342, then they are not to be bundled.
UPDATED:  April 6, 2017