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856 - Electronic Location and Access (R)

MARC 21 Classification - full
December 2020

First Indicator Second Indicator
Access method
# - No information provided
0 - Email
1 - FTP
2 - Remote login (Telnet)
3 - Dial-up
4 - HTTP
7 - Method specified in subfield $2

# - No information provided
0 - Resource
1 - Version of resource
2 - Related resource
8 - No display constant generated

Subfield Codes
  • $a - Host name (R)
  • $c - Compression information (R)
  • $d - Path (R)
  • $f - Electronic name (R)
  • $m - Contact for access assistance (R)
  • $o - Operating system (NR)
  • $p - Port (NR)
  • $q - Electronic format type (NR)
  • $s - File size (R)
  • $u - Uniform Resource Identifier (R)
  • $v - Hours access method available (R)
  • $w - Record control number (R)
  • $x - Nonpublic note (R)
  • $y - Link text (R)
  • $z - Public note (R)
  • $2 - Access method (NR)
  • $3 - Materials specified (NR)
  • $6 - Linkage (NR)
  • $7 - Access status (NR)
  • $8 - Field link and sequence number (NR)


Information needed to locate and access electronic information. The field may be used in a classification 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 classification record or a related electronic resource. This field may also be used to link to an electronic resource intended to supplement the classification scheme, e.g. an image of a map.

Field 856 is repeated when the location elements vary (the URL in subfields $a and $c, when used). It is also repeated when more than one access method is used, mirror sites are recorded, different formats/resolutions with different URLs are indicated, and related items are recorded.

See the Guidelines for the Use of Field 856 for a more thorough discussion on the use of field 856.



First Indicator - Access method

Defines the access method to the electronic resource. The value in this indicator position determines which subfields are appropriate.

If the resource is available by more than one access method, the field is repeated with data appropriate to each method. The methods defined are the main TCP/IP (Transmission Control Protocol/Internet Protocol) protocols.

When recording a URL in subfield $u, the value corresponds to the access method (URL scheme), which is also the first element in the URL string.

# - No information provided
0 - Email

Access to the electronic resource is through electronic mail (email). Includes subscribing to an electronic journal or electronic forum through software intended to be used by an email system.

1 - FTP

Access to the electronic resource is through the File Transfer Protocol (FTP).

2 - Remote login (Telnet)

Access to the electronic resource is through remote login (Telnet).

3 - Dial-up

Access to the electronic resource is through a conventional telephone line (dial-up). Additional information in subfields of the record may enable the user to connect to the resource.

4 - HTTP

Access to the electronic resource is through the Hypertext Transfer Protocol (HTTP).

7 - Method specified in subfield $2

Access to the electronic resource is through a method other than the defined values and for which an identifying code is given in subfield $2 (Source of access).

Second Indicator - Relationship

Relationship between the electronic resource at the location identified in field 856 and the entity described in the record. Only value # (no information provided) is used for classification records.

# - No information provided
0 - Resource
1 - Version of resource
2 - Related resource
8 - No display constant generated


$a - Host name

Fully qualified domain (host name) of the electronic location. It contains a network address which is repeated if there is more than one address for the same host.

$c - Compression information

Information about the compression of a file, in particular, whether a specific program is required to decompress the file.

May be repeated if two compression programs are used, noting the latest compression first.

$d - Path

Path, the series of logical directory and subdirectory names that indicate where a file is stored. The filename itself is recorded in subfield $f. This may be a surrogate path leading the user to the host where complete and current access information is stored in a locator table.

$f - Electronic name

Electronic name of a file as it exists in the directory/subdirectory indicated in subfield $d on the host identified in subfield $a. Subfield $f may be repeated if a single logical file has been divided into parts and stored under different names. In this case, the separate parts should constitute a single bibliographic item. In all other cases, a file that may be retrieved under different filenames contains multiple occurrences of field 856, each with its corresponding electronic name in subfield $f. A filename may include wildcard characters (e.g., * or ?) if applicable. Use subfield $z to explain how files are named, if needed.

$m - Contact for access assistance

Name of a contact for assistance in accessing a resource at the host specified in subfield $a.

$o - Operating system

For informational purposes, the operating system used by the host specified in subfield $a may be indicated here. Conventions for the path and filenames may be dependent on the operating system of the host.

$p - Port

Portion of the address that identifies a process or service in the host.

$q - Electronic format type

Identification of the electronic format type, which is the data representation of the resource, such as text/HTML, ASCII, Postscript file, executable application, or JPEG image. Electronic format type may be taken from enumerated lists such as registered Internet Media Types (MIME types).

The intent of specifying this element is to provide information necessary to allow people or machines to make decisions about the usability of the encoded data (what hardware and software might be required to display or execute it, for example). The electronic format type also determines the file transfer mode, or how data are transferred through a network. (Usually, a text file can be transferred as character data which generally restricts the text to characters in the ASCII (American National Standard Code for Information Interchange (ANSI X3.4)) character set (i.e., the basic Latin alphabet, digits 0-9, a few special characters, and most punctuation marks) and text files with characters outside of the ASCII set, or non-textual data (e.g., computer programs, image data) must be transferred using another binary mode.)

$s - File size

Size of the file as stored under the filename indicated in subfield $f. It is generally expressed in terms of 8-bit bytes (octets). It may be repeated in cases where the filename is repeated and directly follows the subfield $f to which it applies. This information is not given for journals, since field 856 relates to the entire title, not to particular issues.

$u - Uniform Resource Identifier

Uniform Resource Identifier (URI), which provides standard syntax for locating an object using existing Internet protocols. Field 856 is structured to allow for the creation of a URL from the concatenation of other separate 856 subfields. Subfield $u may be used instead of those separate subfields or in addition to them. Subfield $u may be repeated only if both a URN or a URL or more than one URN are recorded.

May be repeated only if both a URN and a URL or more than one URN are recorded. Field 856 is repeated if more than one URL needs to be recorded.

$v - Hours access method available

Hours that access to an electronic resource is available at the location indicated in this field. If the record is for a system or service, the hours of availability are recorded in field 307 (Hours, etc.). This subfield is only used to record hours of availability of the specific location indicated in field 856.

$w - Record control number

System control number of the related record preceded by the MARC code, enclosed in parentheses, for the agency to which the control number applies. The data in the subfield links field 856 to the MARC record having the same data in a control number field. See Organization Code Sources for a listing of organization code sources used in MARC 21 records.

$x - Nonpublic note

Note relating to the electronic location of the source identified in the field. The note is written in a form that is not adequate or intended for public display. It may also contain processing information about the file at the location specified.

$y - Link text

Used for display in place of the URL in subfield $u (Uniform resource identifier). When subfield $y is present, applications should use the contents of it as the link instead of subfield $u linking to the destination in subfield $u.

Use of the link text is independent of any decision concerning the second indicator value.

$z - Public note

Note relating to the electronic location of the source identified in the field. The note is written in a form that is adequate or intended for public display.

$2 - Access method

Access method when the first indicator position contains value 7 (Method specified in subfield $2). Code from: Electronic Access Methods Code List.

$3 - Materials specified

Part of the entity to which the field applies.

$6 - Linkage

See the description of this subfield in Appendix A: Control Subfields.

$7 - Access status

Code indicating the availability of access to the remote electronic resource the address of which appears in subfield $u. Subfield $7 applies to all subfields $u present in the field.

0 - Open access

The remote electronic resource is freely and openly accessible online to everyone, without restriction, login, or payment.

1 - Restricted access

The remote electronic resource is not freely and openly accessible online.

u - Unspecified
z - Other

$8 - Field link and sequence number

See the description of this subfield in Appendix A: Control Subfields.


084 0#$alcc
[Library of Congress Classification]
153 ##$aG1350$cG1352$hAtlases$hBy region or country$hAmerica. Western Hemisphere$hNorth America$hUnited States$hNortheastern States. Eastern United States, 1870 and later$hSouthern States. Confederate States of America$hSouth Central States$jWest South Central States
856 7#$u$yMap of West south central states
[The 856 field links to an image file related to the G schedule (Geography; Maps; Anthropology; Recreation), which consists of a map with references to classification numbers that cover particular areas.]


Spacing underscore and tilde in URLs - In February 1994, additional characters in the MARC character set were defined to both 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.

Many systems have implemented these characters, however, for systems that have not implemented the spacing underscore and tilde, the following alternative characters may be used:

%5F for spacing underscore
%7E for spacing tilde


$b - Access number [OBSOLETE, 2020]
$g - Uniform Resource Name [OBSOLETE, 2000]

Because subfield $g (Electronic name - End of range) was rarely if ever used, it was redefined as Uniform Resource Name in 1997. It was subsequently made obsolete in favor of recording the URN in subfield $u.

$h - Processor of request [OBSOLETE, 2020]
$i - Instruction [OBSOLETE, 2020]
$j - Bits per second [OBSOLETE, 2020]
$k - Password [OBSOLETE, 2020]
$l - Logon [OBSOLETE, 2020]
$n - Name of location of host [OBSOLETE, 2020]
$q - File transfer mode [REDEFINED, 1997]

Subfield $q was defined to contain an indication of whether the file was transferred as binary or ASCII. It was redefined to contain type of electronic format.

$r - Settings [OBSOLETE, 2020]
$t - Terminal emulation [OBSOLETE, 2020]
$u - Uniform Resource Identifier [RENAMED, 2000]

Prior to 1999, subfield $u was defined as Uniform Resource Locator and was repeatable. It was changed to not repeatable because of ambiguity in determining when the subfield could be repeatable. Subfield $u was changed back to repeatable and renamed Uniform Resource Identifier in 2000 to record both URLs and URNs after subfield $g was made obsolete.

$y - Link text [NEW, 2000]
$7 - Access status [NEW, 2019]

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