Library of Congress >> MARC >> Authority >> 8XX >> 856

856 - Electronic Location and Access (R)

MARC 21 Authority - Full
October 2003

First 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

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

Subfield Codes
$a - Host name (R)
$b - Access number (R)
$c - Compression information (R)
$d - Path (R)
$f - Electronic name (R)
$h - Processor of request (NR)
$i - Instruction (R)
$j - Bits per second (NR)
$k - Password (NR)
$l - Logon (NR)
$m - Contact for access assistance (R)
$n - Name of location of host (NR)
$o - Operating system (NR)
$p - Port (NR)
$q - Electronic format type (NR)
$r - Settings (NR)
$s - File size (R)
$t - Terminal emulation (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)
$8 - Field link and sequence number (R)


Information needed to locate and access electronic information. The field may be used in an authority record to provide supplementary information available electronically about the entity for which the record was created.

Field 856 is repeated when the location data elements vary (the URL in subfield $u or subfields $a, $b, $d, 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
Value that defines the access method to the electronic resource. If the resource is available by more than one access method, the field is repeated with data appropriate to each method. 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.
Methods defined are the main TCP/IP (Transmission Control Protocol/Internet Protocol) protocols.
# - No information provided
Used when subfield $g contains a URN and there is no URL recorded in subfield $u. When subfield $u contains a URL and subfield $g is also present with a URN, the indicator value for the appropriate access method of the URL is given.
0 - Email
Access to the electronic resource is through electronic mail (email).Access 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 authority records.
# - No information provided
0 - Resource
1 - Version of resource
2 - Related resource
8 - No display constant generated
Do not apply these indicator values to authority records.


$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.
$b - Access number
Access number associated with a host. It can contain the Internet Protocol (IP) numeric address if the item is an Internet resource, or a telephone number if dial-up access is provided through a telephone line. This data may change frequently and may be generated by the system, rather than statically stored.
May be repeated if all the other information in the field applies.
$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.
$h - Processor of request
Username, or processor of the request; generally the data which precedes the at sign (@) in the host address.
$i - Instruction
Instruction or command needed for the remote host to process a request.
$j - Bits per second
Lowest and highest number of bits (binary units) of data that can be transmitted per second when connected to a host. The syntax for recording the number of bits per second (BPS) should be: <Lowest BPS>-<Highest BPS>. If only lowest given: <Lowest BPS>- ; If only highest given: -<Highest BPS>.
$k - Password
Password required to access the electronic resource. An FTP site may require the user to enter an Internet Protocol address or may require a specific password. Electronically accessed catalogs may also require a password. If a system that requires a password will accept anything entered as valid, this subfield can be omitted from field 856. This subfield is used to record general-use passwords, and should not contain passwords requiring security. Textual instructions about passwords are contained in subfield $z (Public note).
$l - Logon
Characters needed to connect (i.e., logon, login, etc.) to an electronic resource or FTP site. Used to record general-use logon strings which do not require special security.
For many general-use File Transfer Protocol servers, access is gained by entering the string "anonymous." An account number required for login may also be indicated.
$m - Contact for access assistance
Name of a contact for assistance in accessing a resource at the host specified in subfield $a. For addresses relating to the content of the resource itself (i.e. the item represented by the title recorded in field 245) rather than access assistance, field 270 is used. If the address data is the same, use field 270.
$n - Name of location of host
Conventional name of the location of the host in subfield $a, including its physical (geographic) location.
$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. For the operating system of the resource itself (i.e., the item represented by the title recorded in field 245), rather than the operating system of the host making it available, field 753 (Technical Details Access to Computer Files), subfield $c (Operating system) is used.
$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.)
$r - Settings
Settings used for transferring data. Included in settings are: 1) Number Data Bits (the number of bits per character); 2) Number Stop Bits (the number of bits to signal the end of a byte); and 3) Parity (the parity checking technique used). The syntax of these elements is:
<Parity>-<Number Data Bits>-<Number Stop Bits>
If only the parity is given, the other elements of settings and their related hyphens are omitted (i.e., <Parity>). If one of the other two elements is given, the hyphen for the missing element is recorded in its proper position (i.e., <Parity>--<Number Stop Bits> or <Parity>-<Number Data Bits>-). The values for parity are: O (Odd), E (Even), N (None), S (Space), and M (Mark).
$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.
$t - Terminal emulation
Indication of a terminal emulation supported. Terminal emulation is usually specified for remote login (first indicator contains value 2 (Remote login (Telnet))).
$u - Uniform Resource Identifier
Uniform Resource Identifier (URI), which provides standard syntax for locating an object using existing Internet protocols or by resolution of a URN. 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.
May be repeated only if both a URN or a URL or more than one URN are recorded.
$v - Hours access method available
Hours that access to an electronic resource is available at the location indicated in this field. 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 Appendix G 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
Link text is 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).
May include access methods other than the four main TCP/IP protocols specified in the first indicator. The data in this subfield corresponds with the access schemes specified in Uniform Resource Locators (URL) (RFC 1738), a product of the Uniform Resource Identifiers Working Group of the IETF. The Internet Assigned Numbers Authority (IANA) maintains a registry of URL schemes and defines the syntax and use of new schemes. The Library of Congress will include an authoritative list based on that standard in the MARC Code Lists for Relators, Sources, Description Conventions.
$3 - Materials specified
Information that specifies the part of the entity to which the field applies.
$6 - Linkage
See description of this subfield in Appendix A: Control Subfields.
$8 - Field link and sequence number
See description of this subfield in Appendix A: Control Subfields.


856 with URL/URN:
100 1#$aRussell,Bertrand,$d1872-1970
856 4#$u$yphotograph
100 0#$aLeonardo,$cda Vinci,$d1452-1519.$tMona Lisa
856 4#$u$ydescription
856 4#$3image$u
110 2#$aLibrary of Congress.$bCopyright Office
856 4#$u
111 2#$aInternational Conference on the Principles and Future Development of AACR
856 4#$u
150 ##$aPresidents’ spouses$zUnited States
856 4#$u


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
Style for Recording Telephone, Numbers - In subfield $b, periods, spaces, and parentheses used to divide the portions of a number are replaced with hyphens. Numbers are recorded as follows:
<country code>-<area/city code>-<exchange/line number>
Exchange/line number portion often includes internal separators which are replaced by hyphens. If an extension is also given, it is appended to the telephone number preceded by a space and " x".
856 3#$b1-202-7072316$j2400/9600$nLibrary of Congress, Washington, DC$oUNIX$rE-7-1$tvt100$zRequires logon and password


$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.
$u - Uniform Resource Identifier [RENAMED, 2000]
Prior to 1999, subfield $u was defined as repeatable. It was changed to not repeatable in favor of repeating the field due to ambiguity in determining when the subfield could be repeatable. Subfield $u was changed back to repeatable and renamed in 2000 to record URNs after subfield $g was made obsolete.
$y - Link text [NEW, 2000]

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