All federal government agencies/departments are required to send copies of the documents they publish to the U.S. Superintendent of Documents. There they are assigned a SuDoc number, which begins with 1, 2 or 3 letters based on the publishing agency/department; e.g.
ED=Dept. of Education.
HE=Dept. of Health
J=Dept. of Justice
NAS=NASA
PR=President's Office
X=Congress
Y=Congress
and the letters are followed by numbers and often more letters, with all sorts of punctuation in the middle. The basic reference works/indexes used with U.S. Documents cite these numbers, so researchers can easily move from an index to the Government Documents shelves/drawers to find the document they need.
BEWARE: The sorting of SuDoc numbers for shelving/filing is VERY DIFFERENT from the Library of Congress call number sorting. The basic rules for sorting SuDoc numbers are:
Alpha-numeric:Sort by alphabetical letters(s) first, then by numbers The periods between 2 numbers are just dots; they are NOT decimal points.
CORRECT ORDER
C 1.1:992
C 1.2:C 3
C 1.11:25
WRONG ORDER
C 1.1:992
C 1.11:25
C 1.2:C 3
Order of punctuation
: Colons file before / or –
/ Slashes file before –
- Dashes file last