Neb. Rev. Stat. § 60-6,363

For purposes of sections 60-6,363 to 60-6,374 : (1) Diesel-powered motor vehicle shall mean a self-propelled vehicle which is designed primarily for transporting persons or property on a highway and which is powered by an internal combustion engine of the compression ignition type; (2) Motor vehicle shall mean a self-propelled vehicle with a gross unloaded vehicle weight of ten thousand pounds or more or any combination of vehicles of a type subject to registration which is towed by such a vehicle; (3) Smoke shall mean the solid or liquid matter, except water, discharged from a motor vehicle engine which obscures the transmission of light; (4) Smokemeter shall mean a full-flow, light-extinction smokemeter of a type approved by the Department of Water, Energy, and Environment and operating on the principles described in the federal standards; (5) Opacity shall mean the degree to which a smoke plume emitted from a diesel-powered motor vehicle engine will block the passage of a beam of light expressed as a percentage; and (6) Smoke control system shall mean a system consisting of one or more devices and adjustments designed to control the discharge of smoke from diesel-powered motor vehicles.