49 C.F.R. § 223.5
As used in this part-
Administrator means the Administrator of the Federal Railroad Administration or the Administrator's delegate.
Caboose means a car in a freight train intended to provide transportation for crewmembers.
Certified glazing means a glazing material that has been certified by the manufacturer as having met the testing requirements set forth in appendix A of this part and that has been installed in such a manner that it will perform its intended function.
Designated service means exclusive operation of a locomotive under the following conditions:
Emergency window means the segment of a side-facing glazing panel that has been designed to permit rapid and easy removal from inside a passenger car in an emergency situation.
End facing glazing location means any exterior location where a line perpendicular to the plane of the glazing material makes a horizontal angle of 50 degrees or less with the centerline of the locomotive, caboose, or passenger car, including a dome or observation car, except for: The coupled ends of multiple-unit (MU) locomotives or other equipment that is semi-permanently connected to each other in a train consist; and end doors of passenger cars at locations other than the cab end of a cab car or MU locomotive. Any location which, due to curvature of the glazing material, can meet the criteria for either an end facing location or a side facing location shall be considered an end facing location.
FRA means the Federal Railroad Administration.
Incidental freight service means the occasional and irregular use of a locomotive in freight service that is more than 50 years old and used primarily for excursion, educational, recreational, or private transportation purposes.
Locomotive means a self-propelled unit of equipment designed primarily for moving other equipment. It does not include self-propelled passenger cars.
Locomotive cab means that portion of the superstructure designed to be occupied by the crew while operating the locomotive.
Passenger car means a unit of rail rolling equipment intended to provide transportation for members of the general public and includes self-propelled cars designed to carry baggage, mail, express or passengers. This term includes a passenger coach, cab car, and an MU locomotive.
Person includes all categories of entities covered under 1 U.S.C. 1 , including, but not limited to, a railroad; any manager, supervisor, official, or other employee or agent of a railroad; any owner, manufacturer, lessor, or lessee of railroad equipment, track, or facilities; any passenger, any trespasser or nontrespasser; any independent contractor providing goods or services to a railroad; and any employee of such owner, manufacturer, lessor, lessee, or independent contractor.
Railroad means:
Rebuilt locomotive, caboose or passenger car means a locomotive, caboose or passenger car that has undergone overhaul which has been identified by the railroad as a capital expense under Surface Transportation Board accounting standards.
Side facing glazing location means any location where a line perpendicular to any plane of the glazing material makes an angle of more than 50 degrees with the centerline of the locomotive, caboose or passenger car. A side facing glazing location also means a location at the coupled ends of MU locomotives or other equipment that is semi-permanently connected to each other in a train consist, and a location at end doors other than at the cab end of a cab car or MU locomotive.
Windshield means the combination of individual units of glazing material of the locomotive, passenger car, or caboose that are positioned in an end facing glazing location.
Yard is a system of auxiliary tracks used exclusively for the classification of passenger or freight cars according to commodity or destination; assembling of cars for train movement; storage of cars; or repair of equipment.
Yard caboose means a caboose that is used exclusively in a single yard area.
Yard locomotive means a locomotive that is operated only to perform switching functions within a single yard area.
49 C.F.R. §223.5