44 U.S. Code § 719 - Classification and numbering of publications ordered printed by Congress; designation of publications of departments; printing of committee hearings
Publications ordered printed by Congress, or either House, shall be in four series, namely:
one series of reports made by the committees of the Senate, to be known as Senate reports;
one series of reports made by the committees of the House of Representatives, to be known as House reports;
one series of documents other than reports of committees, the orders for printing which originate in the Senate, to be known as Senate documents; and
one series of documents other than committee reports, the orders for printing which originate in the House of Representatives, to be known as House documents.
The publications in each series shall be consecutively numbered, the numbers in each series continuing in unbroken sequence throughout the entire term of a Congress, but these provisions do not apply to the documents printed for the use of the Senate in executive session. Of the “usual number”, the copies which are intended for distribution to State libraries and other designated depositories of annual or serial publications originating in or prepared by an executive department, bureau, office, commission, or board may not be numbered in the document or report series of either House of Congress, but shall be designated by title and bound as provided by section 738 of this title; and the departmental edition, if any, shall be printed concurrently with the “usual number.” Hearings of committees may be printed as congressional documents only when specifically ordered by Congress or either House.