18 CFR § 367.4010 - Account 401, Operation expense.

There must be shown under this caption the total amount included in the service company operation expense accounts 500 through 589 (§§ 367.5000 through 367.5890), 800 through 881 (§§ 367.8000 through 367.8810) and 901 through 931 (§§ 367.9010 through 367.9310).