An additional requirement is that the whiskey all be produced "by the same distiller at the same distillery." That always has struck me as strange, as if he kicked the bucket during the season, it would preclude all of the whiskey being bonded. Maybe they could bottle separate bonded batches
Many "distillers" had whiskey made for them at other "distilleries" in a D.B.A. format. They could not mingle such whiskey with other barrels produced on their own premises (even though from the same distilling season) and call it B.I.B.