49 CFR §553.15

1. (a)Each notice of proposed rulemaking, and each direct final rule, is published in the Federal Register, unless all persons subject to it are named and are personally served with a copy of it.
2. (b)Each notice, whether published in the Federal Register or personally served, includes
   1. (1)A statement of the time, place, and nature of the rulemaking proceeding;
   2. (2)A reference to the authority under which it is issued;
   3. (3)A description of the subjects and issues involved or the substance and terms of the rule.
   4. (4)A statement of the time within which written comments must be submitted; and
   5. (5)A statement of how and to what extent interested persons may participate in the proceedings.