Subzone. Subzone is a special-purpose zone established as part of a zone project for a limited purpose, that cannot be accommodated within an existing zone. The term zone also applies to a subzone, unless specified otherwise.
19 CFR § 146.1
The following words, defined in section 1 of the Foreign-Trade Zones Act of 1934, as amended (19 U.S.C. 81a), are given the same meaning when used in this part, unless otherwise stated: Board, Grantee, and Zones.