Dual-fuel
Dual-fuel means relating to an engine designed for operation on two different fuels but not on a continuous mixture of those fuels (see 1042.601). For purposes of this part, such an engine remains a dual-fuel engine even if it is designed for operation on three or more different fuels. Note that this definition differs from MARPOL Annex VI.
Source
40 CFR § 1042.901
Scoping language
The following definitions apply to this part. The definitions apply to all subparts unless we note otherwise. All undefined terms have the meaning the Clean Air Act gives to them. The definitions follow: