Can anyone decipher the exact meaning of Old Hickory's bat codes (which began this year per MLB's imperative)?

For instance, here are some from my favorite player, Brandon Allen:

903050-BA6
903050-BA8
908154-BA9

...I'm guessing the first five numbers are the date in YMMDD format. Any idea what the last number before the dash, or the last number after his initials are? I'd guess something like order # and the bat # of that particular order.

Maybe others with some Old Hickorys can help nail it down.