It is expected that carriers will first assign to freight service or to passenger service, including allied services, the operating expenses that are directly or naturally assignable and that this direct assignment will be carried to the fullest extent that is practicable, except as stated below, without undue increase in accounting expense. The methods indicated under the various accounts are for dividing the common expenses. The separation should, as far as practicable, be made by operating or accounting divisions, and the aggregate of the divisional separations reported for the year.
Maryland. Public Service Commission, "Rules governing the separation of operating expenses between freight service and passenger service on large steam railways: Issue of 1920: Effective on January 1, 1920" (1919). State Publications. 16.