CFR > Title 1 - General Provisions > CHAPTER I—ADMINISTRATIVE COMMITTEE OF THE FEDERAL REGISTER > SUBCHAPTER E—PREPARATION, TRANSMITTAL, AND PROCESSING OF DOCUMENTS (parts 15 to 22) > PART 21—PREPARATION OF DOCUMENTS SUBJECT TO CODIFICATION > SUBPART A—General (§21.1 to §21.35) > 21.12—Reservation of numbers.