PROPOSAL NO.: 2000-07

DATE: May 10, 2000

NAME: Definition of Subfield $y (Link text) in Field 856 in all Formats

SOURCE: Florida Center for Library Automation

SUMMARY: This paper proposes the addition of subfield $y in field 856 to record link text to be used in an online display instead of the URL.

KEYWORDS: Field 856; Electronic Location and Access; Link text; Subfield $y, in field 856



05/10/00 - Forwarded to the MARC Advisory Committee for discussion at the July 2000 MARBI meetings.

07/09/00 - Results of MARC Advisory Committee discussion - Approved.
It was recommended that application guidelines should state that the use of the link text is independant of any decision concerning the second indicator value. LC should look at other fields where subfield $u is defined to consider whether a subfield for link text is also needed.

07/27/00 - Results of LC/NLC review - Approved.

PROPOSAL NO. 2000-07: Definition of Subfield $y (Link text) in Field 856 in all Formats


Field 856 (Electronic Location and Access) has several places to record information to help the public in interpreting a URL. This data may be used by an application such as an online public catalog or commercial search service when generating a display. Some of the relevant data elements include:

1.1. Second indicator (Relationship)

The second indicator contains a value that identifies the relationship between the electronic resource at the location identified in field 856 and the item described in the record as a whole. Recommended display constants are as follows:

blank = "Electronic resource"
0 = "Electronic resource"
1 = "Electronic version"
2 = "Related electronic resource"

1.2. Subfield $3 (Materials specified)

Subfield $3 may be used to indicate the part of the resource to which the URL applies (MARC 21) or to describe the related resource pointed to by the URL (Guidelines for the Use of Field 856, Revised August 1999):

$3Finding aid
$3Author self-portrait

1.3. Subfield $z (Public Note)

According to the Guidelines for the Use of Field 856, "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.)"

856 4 $z Online version: $u
(Could generate link text from the data in $z if the system is programmed to do so)


There is an assumption that the URL itself will be displayed to the user, with display constants and additional text when appropriate, e.g.:

856 4#$3Table of contents $u
would generate something like:
Table of contents:

856 40$u
would generate something like:
Electronic resource:

In a large number of applications, however, including both commercial services and library catalogs and portal pages, the actual URLs are not displayed, but rather some text or icon is provided for the user to click on. URLs themselves are often quite lengthy and are full of odd character sequences which are unattractive at best, and can be intimidating to the user at worst. Occasionally they contain data such as security information which a service provider may just as soon not have displaying obviously to the user.

2.1. HTML anchor

In HTML-encoded files, the HTML anchor (<a>) tag is designed to allow any text to be displayed as the clickable link. The generic form of the anchor is

<A HREF="any-url">any-displaying-text</A>

where "any-url" is known as the destination anchor and "any-displaying-text" is known as the link text. Browsers will display the link text which, when clicked, will invoke the non-displaying destination anchor.

For example:
<A HREF=""></A>
would display:
as a clickable link

<A HREF="">United States Code, Title 17</A>
would display:
United States Code, Title 17
as a clickable link.

Both links would go to the destination:

2.2. 856 link text

There is no place in the current field 856 to record text meant explicitly to display in place of the URL in $u as the link text. It is, of course, possible for any application to be programmed to use any subfield for this purpose. Many current applications are programmed to use the contents of $3 or the contents of $z as the link text. For example, an application could take the data in:

856 4#$3Table of contents $u
and use it to generate the display "Table of contents"
as a clickable link, by creating an anchor of the form
<A HREF="">Table of contents</A>
i.e. <A HREF="[data in $u]">[data in $3]</A>

Although this may work within a particular application, there is no uniformity across applications because there is no uniform method recommended or specified within MARC. This limits the ability to share data, since a form of 856 which works well in a catalog that displays $3 as link text will not work well in a catalog that displays $z as link text. Institutions are at times using the defined subfields inappropriately to overcome the lack of a specific subfield for link text.

This also limits flexibility, especially in the case where $3 and $z are needed for content that differs from the desired link text. For example, imagine an application that makes every resource available as both JPEG and PDF type files, where the institution needs subfield $3 to indicate the part of the bibliographic unit being pointed to, and subfield $z for notes about access rights that vary from resource to resource. The desired link text is "Click here for JPEG version" and "Click here for PDF version" respectively. There is no place in field 856 to specify specific link text, nor can that text be supplied as a constant, as it will vary depending upon the image file format.

Representatives from several library management system vendors have indicated that their companies would be happy to program the use of link text if there were a consistent place to put it.

It might be noted that if 856 subfield $y is defined that only one alphabetic subfield ($e) will be available for use. However, some of the 856 subfields are not used, having been defined in 1993 when the Internet was very different from today (and before URLs were as standardized as they are now). It is possible that if the need arises one of those unused subfields could be redefined if it is determined that they have not been used.


In field 856 (Electronic Location and Access) in all MARC 21 formats:

Library of Congress Library of Congress
Library of Congress Help Desk (01/26/01)