VERIFIED SOLUTION i

"BG MAX thickness <= BL MAX thickness" Bundle size creation using conflicting "BL MAX" and "BG MAX" parameters appears to not work as expected in MailStream Plus

MailStream Plus™, all versions, all platforms
There is a potential error/warning  message provided in the MailStream Plus™ Guide-
"BG MAX thickness <= BL MAX thickness"

The Description for the message is-
"The MAXIMUM bag thickness is less than or equal to the bundle max thickness. MailStream Plus requires that the Container maximum thickness be greater than the Bundle maximum thickness. Otherwise, bundles could be created that will not go into a container."

That seems to say that if BG MAX (Tray/Bag Maximum) for a tray or sack is set to, say, 20.00 inches in positions 40-44 (max container thickness)
---and---
then if the same job has a BL MAX (Bundle Maximum) set to, say, 25.00 inches in positions 30-34 (maximum bundle thickness)
---then---
That would result in making 25" bundles which would be too large to fit into 20" trays/sacks.

But what actually happens in many cases like this (including possibly in both letters and flats mailings) is that a single bundle will end up being made in the trays/sack at the BG MAX's thickness limit.
This is because the way the presort actually works is that first 'logical' bundles are made, with all of the pieces in them. Then the pieces are physically put into the containers, using whatever thickness limit (or other limit) there is on the BG MAX.

So although the error/warning mentioned at the beginning of this article may be seen at some times, in many jobs there will not be an an actual error.  Because BL MAX will not have an effect, due to the BG MAX maximum thickness being used for the actual placing of the pieces into trays/sacks.
UPDATED:  May 16, 2019