Guidelines for the Use of Field 856

Revised August 1999


Network Development and MARC Standards Office
Library of Congress

August 1999 Revision. This document gives guidelines on the use of field 856 and is current as of July 1999. It includes all changes to the field through the annual ALA conference held in June 1999. It is superseded by the March 2003 edition of the guidelines.

A description of the full field is available in the MARC 21 Concise Format for Bibliographic Data, Field 856 or in the full format, MARC 21 Format for Bibliographic Data, available from LC's Cataloging Distribution Service.

Field 856 in the MARC 21 Bibliographic, Holdings, Authority, Classification, and Community Information formats is used for Electronic Location and Access information to an electronic resource and contains information related to the resource. The field may be used in a bibliographic or holdings record for a resource when that resource or a subset of it is available electronically. In addition, it may be used to locate and access an electronic version of a non-electronic resource described in the bibliographic record, part of the resource, or a related electronic resource. In an authority record it contains the electronic location information about the entity authorized by the record.

Field 856 contains the following elements:

856 Electronic Location and Access (R)


Access method
No information provided
Remote login (Telnet)
Method specified in subfield $2

No information provided
Version of resource
Related resource
No display constant generated

Subfield Codes

Host name (R)
Access number (NR)
Compression information (R)
Path (R)
Electronic name (R)
Uniform Resource name (R)
Processor of request (NR)
Instruction (R)
Bits per second (NR)
Password (NR)
Logon (NR)
Contact for access assistance (R)
Name of location of host (NR)
Operating system (NR)
Port (NR)
Electronic format type (NR)
Settings (NR)
File size (R)
Terminal emulation (R)
Uniform Resource Locator (NR)
Hours access method available (R)
Record control number (R)
Nonpublic note (R)
Public note (R)
$2 Access method (NR)
$3 Materials specified (NR)
$6 Linkage (NR)
$8 Field link and sequence number (R)

General Information

The data in field 856 may be a Uniform Resource Locator (URL), which is recorded in subfield $u, or it may parse the necessary locator information into separate defined subfields. An access method, or protocol used, is given as a value in the first indicator position (if access method is email, ftp, telnet, dial-up, or HTTP) or in subfield $2 (if access method is anything else). The access method is also the first element of the URL. The data may include a URN (e.g., a DOI or handle) in subfield $g.

When more than one access method is used or when the location data elements vary (i.e., the URL in subfield $u or subfields $a, $b, and $d when used), the field is repeated.

Uniform Resource Locator. For any access method, a Uniform Resource Locator (URL) may be used in subfield $u. A URL may also be used in subfield $u in addition to the separate subfields, if it is desirable to display data in a particular way from the separate subfields.

The most commonly used data elements of field 856 are as follows:
1st indicator = 4 for HTTP (earlier records may use blank)
Subfield $u = [HTTP URL]
Subfield $3: data specifying what URL refers to, if applicable
Subfield $z (Public note): data ...

Required subfields. If a URL is used to provide access it is recorded in $u. If the electronic location and access information is parsed into separate subfields, no single subfield is required in all cases. When parsing the elements into subfields rather than using a URL in $u, which ones are used largely depends on the access method indicated in the first indicator or in $2 (if first indicator = 7). See Attachment B for a list of the most likely subfields to be used depending upon the first indicator value.

Encoding non-USMARC characters. In February 1994 Proposal 93-10 was approved, which called for additional characters in the MARC character set both to accommodate existing bibliographic needs and to align it with the ASCII and ANSEL character sets. Both the spacing underscore and the spacing tilde were added at the time because of the need in directory and file names for electronic resources. The major bibliographic utilities and the Library of Congress have not yet implemented these character set changes, primarily because of other conflicting demands and the impact of such changes. However, some URLs require encoding directory and file names that contain the spacing underscore or spacing tilde. The method to be used for encoding is the percentage sign with the hex code value of the character. Although this is not a MARC 21 convention, it is specified for use in the URL standard (RFC1738, section 2.2).

The following could be used in MARC records:
spacing underscore %5F
spacing tilde %7E
Since these characters are valid ASCII strings, the method allows for the functionality supported by Z39.50 clients and Web browsers which permit the user to click on a link to access the resource represented by the URL. When the additions to the MARC 21 character set are implemented to support the encoding of these spacing characters, it would be possible to replace all instances of %xx strings. It is expected that implementation of character set changes will occur in January 2001. Further announcements will be forthcoming.

Multiple 856 fields. There are many reasons to include multiple 856 fields in records. Following are the most common examples:

Field 856 in bibliographic or holdings records. Since field 856 is a field that is valid in both bibliographic and holdings records, institutions may favor recording it in the holdings record. It is intended to be an electronic equivalent to field 852 (Location), which contains information to locate a physical item, identifying the holding organization and other detailed information required to locate the item in a collection. In early 1999 the Network Development and MARC Standards Office elicited opinions on whether it is desirable to use the field in bibliographic or holdings records. Responses received generally favored recording the field in the holdings record where practical. However, for a variety of reasons, one being the wider exchange of bibliographic records, many institutions use the bibliographic record despite the benefits of using holdings. However, some have been able to use the holdings record, and the following advantages were expressed:

In order to move towards this approach in the future, it will be necessary to persuade vendors to make some changes to their ILS systems:

At this point it is a local decision whether to use the field in bibliographic or holdings records.

Specific data elements

First Indicator (Access Method). The first indicator contains information about access method to the resource and has values defined for Email, FTP, Telnet, Dial-up, and HTTP. Access methods without defined values may contain a first indicator value 7 with the method indicated in $2. Older records may contain value 7 and subfield $2 (with content http) if created before value 4 (HTTP) was defined.

The list of indicator values and the values used in subfield $2 is specified in the URL standard (RFC1738) and maintained by the Internet Assigned Numbers Authority (IANA). Additional schemes are documented by IANA in URL schemes.

For those access methods that do have an indicator value defined (ftp, telnet, electronic mail), the URL is recorded in $u with the appropriate indicator value recorded, even though it is redundant with the first element of the URL.

Value # (blank) (No information provided) may be used if only a URN is recorded in subfield $g; if both a URL is recorded in $u and a URN in $g, the first indicator is set for the URL access method. If using a URL in subfield $u with one of the access methods that has a value defined in the first indicator, the access method may be repeated in $2 if desired. (e.g. 856 0# $ $2mailto)

Value 7 and subfield $2 file is used for electronic access to host-specific file names (i.e., files stored locally). This designation is also a defined URL scheme.

Second indicator (Relationship). A second indicator is provided to show the relationship between the information in field 856 and the resource described in the record. This may be used for generation of a display constant or for ordering multiple 856 fields. For further information see Proposal No. 97-1 (Definition of Second Indicator (Relationship to Source) in Field 856 in the MARC Formats). Suggested display constants for the indicator values are:

# (blank) Electronic resource:
0 Electronic resource:
1 Electronic version:
2 Related electronic resource:
8 [no display constant generated]

Subfield $3 (Materials specified). Subfield $3 is used to specify to what portion or aspect of the resource the electronic location and access information applies. Specific situations may be:

Subfield $q (Electronic format type). Subfield $q was originally defined as File transfer mode, to include "binary" or "ascii". It was redefined in June 1997 as Electronic format type to accommodate an Internet Media Type (MIME type). Alternatively, textual information on the electronic format type may be recorded.

Subfield $u (URL) repeatability. Proposal No. 99-06 (Repeatability of subfield $u (URL) in field 856 of the MARC formats), which proposed making subfield $u non-repeatable, was approved by the MARC Advisory Committee in January 1999. This requires that multiple URLs need to be recorded in repeated 856 fields.

Persistent Uniform Resource Locators (PURLs) have been implemented at OCLC and are intended to deal with the problem of changeable URLs. Functionally, a PURL is a URL, but it is intended to point to an intermediate resolution service. Its persistence depends upon the updating of a PURL database when the location of the resource changes. When recorded in an 856 field, it is intended to allow for persistence so that each record containing the URL need not be updated when the location changes. Since the PURL is supposed to provide persistent access to the resource, it can be argued that there is no reason to retain the URL that might become invalid. However, this is an internal decision, and institutions that use PURLs and wish to retain the original URL should use subfield $x (Nonpublic note) for this purpose. This is an appropriate subfield, since it may not be desirable to display the URL to the public because it could cause confusion, but it would allow for its retention in the record.

OCLC has used PURLs in records in its INTERCAT database, a catalog of Internet resources. Records containing field 856 are selected from WorldCat and each resource described in the record is assigned a PURL and registered in the PURL database. The PURL is recorded in 856$u and the URL originally in the record is transferred to subfield $z (Public note), because OCLC wanted to retain the information originally input in the record. This use of subfield $z is peculiar to INTERCAT, and it should be noted that these records reside only in INTERCAT and are not distributed with the URL in subfield $z.

Subfield $z (Public Note). Subfield $z may be used for any additional notes about the electronic resource at the specified location. Examples include subscription information or access restrictions.

Example for a mailto URL: $zInclude desired file format following the hyphen in the filename: EID0ASCII, EID-PDF or EID-PS.

Institutions have used subfield $z in various ways. Some have created a note for display repeating the URL in $u. (It would be preferable for systems to display $u rather than have those preparing records record information redundantly.)


URLs in fields other than field 856. In June 1999 the approval of Proposal No. 99-08 (Defining URL/URN subfields in the MARC 21 Bibliographic Format) resulted in the definition of a subfield $u (URI) in two other fields. These are:

Subfield $u was defined to contain a URL or URN for a finding aid or action note available electronically. It is likely that the MARC Advisory Committee will consider the definition of URI subfields in other bibliographic fields as requests are submitted.

Note that subfield $u in these two fields was defined as repeatable, since the field may require recording both a URL and URN associated with the resource. The documentation will stipulate that the subfield may only be repeated in the latter case, not for repeated URLs.

LC usage. Field 856 has been used at the Library of Congress as follows.
Records for resources that have been digitized (or otherwise made available electronically) as part of the National Digital Library Program (American Memory) may contain field 856. Generally, the field is added to the record for the original item, rather than a new record created (unless it consists of components that have been gathered together and only exist as an entity in electronic form). In some cases, LC has recorded a handle, which is a Uniform Resource Name in field 856 subfield $g. The URN will be able to be resolved by a handle server and the electronic resource retrieved in the future. Until this resolution is possible LC will record both a URL in $u that points to a proxy server with the URN (handle) attached and a plain URN (handle) in $g.

Field 856 in other formats. Field 856 is also defined in the Authority, Classification, and Community Information Formats. It may be used as follows:

Attachment A shows a few LC examples illustrating the use of field 856.

Attachment B gives information on subfield use when a URL is not recorded in $u.

For a full description of the field see: MARC 21 Concise Format for Bibliographic Data: Field 856.


* System supplied element
# Blank
$ Subfield code delimiter

Record #1: 856 link to a subset of the bibliographic item; HTTP URL

Leader *****nam##*******#a
001 $a93-3471$cr95
005 $a19950215082838.3
008 950215s1994####enk######b#####||||#eng#
040 $aDLC $cDLC $dDLC
050 00$aHA29$b.A5828 1993
082 00$a300/.1/5195 $220
245 00 $aAnalyzing qualitative data /$cedited by Alan Bryman and Robert G. Burgess.
260 $aLondon ;$aNew York :$bRoutledge,$c1994.
300 $axii, 232 p. :$bill. ;$c24 cm.
504 $aIncludes bibliographical references and index.
020 $a0415060621
020 $a041506063X (pbk.)
650 #0$aSocial sciences $xStatistical methods.
650 #0$aSocial sciences $xResearch $xMethodology.
700 10$aBryman, Alan.
700 10$aBurgess, Robert G.
856 4#$3Table of contents $u

Record #2: 856 link to item itself; HTTP URL

Leader *****nmm##*******#a
001 $a94-790547
005 $a19950106130304.3
008 950106s1994####dcun#######m########eng##
040 $aDLC $cDLC $dDLC
050 00$aZ695.615
082 10$a025.3 $212
111 2$aSeminar on Cataloging Digital Documents $d(1994 : $cUniversity of Virginia Library and Library of Congress)
245 10$aProceedings of the Seminar on Cataloging Digital Documents, October 12-14, 1994 $h{computer file} /$cUniversity of Virginia Library, Charlottesville, and the Library of Congress.
256 $aComputer data and program.
260 $a{Washington, D.C. :$bLibrary of Congress,$c1994}.
538 $aAccess: Internet. Address:
500 $aTitle from title screen.
500 $a"Sponsor: Sarah Thomas, director for cataloging, Library of Congress"--Home page.
520 #$aText, graphics, and audio files, including a summary of the seminar by Sarah Thomas, color photographs of the presenters and various events, texts of the presentations, notes taken by Library of Congress staff, records of the panel discussion, an action plan, and a list of participants.
650 #0$aCataloging of computer files $xCongresses $xDatabases.
700 1# $aThomas, Sarah.
710 2#$aUniversity of Virginia. $bLibrary.
710 2#$aLibrary of Congress.
856 40$u

Record #3: 856 with Second Indicator Value 2 for Related electronic resource. Record describes the original manuscript collection; 856 field describes the finding aid for the electronic version of that original.

Leader *****npc##*******#e
001 mm78052522
008 780918||||||||||||#################eng
010 $amm 78052522 $bms 69002041
040 $aDLC$cDLC
072 7$aL$2lcmd
100 1$aJackson, Shirley,$d1919-1965.
245 00$kPapers,$f1932-1970$g(bulk 1932-1965)
300 $a7,400$fitems.
300 $a51$fcontainers.
300 $a20.4$flinear feet.
520 8 $aCorrespondence; diaries; journals; mss., typescripts, and galleys of articles, books, and short stories; college notebooks; watercolors; pencil and ink drawings; and other papers pertaining primarily to Jackson's writings. Includes mss., notes, and outlines relating chiefly to the development of Jackson's short stories through which she conveyed her perception of psychological horror lying just beneath the surface of modern life, as well as to her supernatural tales and to her humorous stories of contemporary domestic life. Correspondents include Jackson's husband, Stanley Edgar Hyman, her parents, Leslie H. and Geraldine B. Jackson, Walter Bernstein, Jean Brockway, Elizabeth Batterham ("Libby") Burke, John Ciardi, Pascal Covici, Carol Black Livaudais, June Mirken Mintz, Frank Orenstein, Louis L. Scher, Mary Shaw, Robert M. Strauss, Louis Untermeyer, Jay Williams, the publishing firm of Farrar, Straus and Young, and Jackson's literary agents Brandt & Brandt and the Music Corporation of America.
541 $cGift,$aStanley Edgar Hyman,$d1967.
541 $cTransfer,$aStanley Edgar Hyman papers,$bLibrary of Congress Manuscript Division,$d1979.
541 $cGift,$aVirginia M. Olsen,$d1991.
544 $3Audiotape$etransferred to$aLibrary of Congress Motion Picture, Broadcasting, and Recorded Sound Division.
544 $3Selected artifacts$etransferred to$aSmithsonian Institution.
545 $aAuthor.
555 8 $aFinding aid available in the Library and on Internet.
600 10$aBernstein, Walter.
600 10$aBrockway, Jean.
600 10$aBurke, Elizabeth Batterham.
600 10$aCiardi, John,$d1916-
600 10$aCovici, Pascal,$d1930-
600 10$aHyman, Stanley Edgar,$d1919-1970.
600 10$aJackson, Geraldine B.
600 10$aJackson, Leslie H.
600 10$aLivaudais, Carol Black.
600 10$aMintz, June Mirken.
600 10$aOrenstein, Frank.
600 10$aScher, Louis L.
600 10$aShaw, Mary.
600 10$aStrauss, Robert M.
600 10$aUntermeyer, Louis,$d1885-1977.
600 10$aWilliams, Jay,$d1914-
610 20$aBrandt & Brandt.
610 20$aFarrar, Straus and Young.
610 20$aMusic Corporation of America.
650 0$aAmerican fiction.
650 0$aHorror tales, American.
650 0$aHumorous stories, American.
650 0$aShort stories, American.
650 0$aSupernatural in literature.
656 7$aAuthors.$2itoamc
852 $aLibrary of Congress$bManuscript Division$eWashington, D.C.
856 42$3Finding aid$u

ATTACHMENT B: Subfield Use When Not Using $u(URL)

If 1st indicator = 0 (email) and a URL is not recorded in $u, the following subfields are used:
$a Host name
$f Electronic name
May also use: $b, $h, $i, $m, $n, $s, $x, $z
Unlikely to use: $c, $d, $k, $l, $o, $p, $t, $2
Those not listed can theoretically be used but no examples have been identified. This is equivalent to URL mailto: scheme.

If 1st indicator = 1 (ftp) and a URL is not recorded in $u, the following subfields are used:
$a Host name (or can use unique elements in $d and/or $f below and omit $a)
$d Path
$f Electronic name
May also use: $b, $c, $g, $i, $k, $l, $m, $n, $o, $p, $q, $s, $x, $3
Unlikely to use: $h, $t, $2
Those not listed can theoretically be used but no examples have been identified. This is equivalent to URL ftp: scheme.

If 1st indicator = 2 (Remote login) and a URL is not recorded in $u, the following subfield is used:
$a Host name
May also use: $b, $k, $l, $m, $n, $o, $p, $t, $x, $z, $3
Unlikely to use: $c, $d, $f, $g, $q, $s, $2
Those not listed can theoretically be used but no examples have been identified. This is equivalent to URL telnet: scheme.

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