off-highway business use
(1) Exemption for off-highway business use (A) In general No tax shall be imposed by subsection (a) on liquids sold for use or used in an off-highway business use. (B) Tax where other use If a liquid on which no tax was imposed by reason of subparagraph (A) is used otherwise than in an off-highway business use, a tax shall be imposed by paragraph (1)(B), (2)(B), or (3)(A)(ii) of subsection (a) (whichever is appropriate) and by the corresponding provision of subsection (d)(1) (if any). (C) Off-highway business use defined For purposes of this subsection, the term “off-highway business use” has the meaning given to such term by section 6421(e)(2); except that such term shall not, for purposes of subsection (a)(1), include use in a diesel-powered train.