Okla. Stat. tit. 66, § 66-93: Injuries to persons

In case any passenger on any railroad shall be injured while on

the platform of a car while in motion, or in any baggage, wood or

freight car, in violation of the printed regulations of the

corporation posted up at the time in a conspicuous place inside of

its passenger cars then in the train, such corporation shall not be

liable for the injury, if it had furnished room inside its passenger

cars sufficient for the accommodation of its passengers.