27 CFR 24.27: Segregation of operations.

The appropriate TTB officer may require the proprietor to segregate operations within any wine premises established under this part, by partitions or otherwise, to the extent deemed necessary to prevent jeopardy to the revenue, to prevent confusion between operations, to prevent substitution with respect to the several methods of producing effervescent wine, and to prevent the commingling of standard wine with other than standard wine.