11-Salaries and wages,
21-Materials, tools, supplies, fuels, and lubricants,
41-Other purchased services, and
61-General.
These natural expenses shall be individually applied to the separation rules in §1242.10. In each case, the independent accounts providing the basis for freight/passenger separation of the dependent account shall have the same natural expense designation. For example, the basis of separating account 11-19-02, Salaries and Wages, Way and Structures, Administration-Track, would be based on certain independent accounts including 11-17/18-10, Salaries and Wages, Way and Structures, Running/Switching, Repair and Maintenance, Roadway.
49 C.F.R. § 1242.06