Catalog of U.S. Government Publications.

Connecting to GPO's CGP via Z39.50

Z39.50 is a national, as well as international, standard, which defines protocol for computer-to-computer information retrieval. It was developed by the National Information Standards Organization (NISO), an American National Standards Institute (ANSI)-accredited standards development body. It is covered by the International Organization for Standardization (ISO) standard 23950.

The U.S. Government Printing Office (GPO)'s Catalog of U.S. Government Publications (CGP) uses Ex Libris' ALEPH 500 software, which allows users to connect to the CGP with any Z39.50 client. Records supplied by GPO via Z39.50 are encoded in MARC8. MARC8 is the bibliographic data interchange format used by the CGP for Z39.50 record export.

Connection settings to access GPO's CGP via Z39.50:

Username and Password Information

Access to the CGP via Z39.50 for searching, retrieval and downloading of bibliographic records is limited to depository libraries. The password for access is found in the Federal Depository Library Directory (FDLD) at .

To access the password:

  1. Login to the Directory;
  2. Select Edit User Information under Options;
  3. The password appears in the Z39.50 Password field.
Please note the "user name" for Z39.50 is always "z39" as a convention in the Z39.50 protocol.

Z39.50 Bib-1 USE Attributes

The following bib-1 'use' attributes are supported by GPO's Z39.50 configuration.

For Keyword Searches:
Field Use-value
All Keywords 1016
Author Keyword 1003
Title Keywords 4
Series Title 5
Subject Heading 21
Year 31
System Number 12
OCLC Number 1007
Stock Number 1028
SuDoc Number** 50
Item Number**** 1224
Notes 63
PURL (LPS#) 1032
Record Date and Time Stamp (005) 1012

For Browse or Phrase Searches:
Field Use-value
SuDoc Number 50
Author Keyword 1003
Title Keywords 4
Author-Personal Name 1004
Coporate Author 1005
Subject Heading 21
LC Subject Heading 27
MeSH Heading 25
LC Classification Number 16

Sort Options:
sort 02 1 Author
sort 03 4 Title
sort 01 30 Year
sort 02 1003 Author

** Please Note: When performing the SuDoc Number searches in some Z39.50 clients, you may have to replace all occurrences of spaces (" ") with a caret symbol ("^") in your search term.

Example: The SuDoc number "HE 20.7008:H 35" replace the spaces with carets (^) such as "HE^20.7008:H^35" .

For more information on this issue, please visit our Z39.50 FAQs at:

****Please Note: GPO Item Number (MARC tag 074)is a newly created Z39.50 Bib-1 use attribute proposed by GPO, and approved and implemented by the Z39.50 Standard Maintenance Agency. The assigned value to this attribute is "1224". In order to search by Item Numbers via Z39.50, you have to set up the Bib-1 attribute (1(u)=1224) in your Z39.50 gate configuration. However, due to the filing configuration restriction in GPO's ILS you have to search the Item Number (MARC tag 074) with no space between the Item Number and Format.

Examples: 0834-W-06(online) or, @attr 1=1224 0834-W-06(online)

For more information on this issue, please visit our Z39.50 FAQs at:

Diacritics and Z39.50 Searching

Aleph clients support diacritics, as other Intgrated Library System clients also may; however, for some Z39.50 clients, such as MarcEdit, diacritics may not be supported, and can cause a problem when searching. If you find that your Z39.50 client has difficulties with diacritics, please replace the diacritics with the Romanized equivalent. For example, if you search the Spanish title "Ahorro de energía" you should replace the diacritic "í" with the Romanized equivalent "i" in the Z39.50 search.

Further Help or Information about Z39.50

For more information about GPO's Z39.50 via the CGP, please visit our Z39.50 FAQs at:

The Library of Congress (LC) is the official Z30.50 Maintenance Agency. At LC's Z39.50 web site (, one can find more extensive documentation on various aspects of Z39.50, from protocol and attribute descriptions to a web Gateway page.

For GPO's assistance with our Z39.50 access, please use askGPO at the following link: AskGPO. We have established a subcategory "Z39.50" under the category "Federal Depository Libraries" under the subcategory heading "CATALOG OF U.S. GOVERNMENT PUBLICATIONS" for this purpose.