PROPOSAL NO.: 2003-02

DATE: Dec. 16, 2002

NAME: Definition of subfield $u (URI) in Field 538 (System Details Note) in the MARC 21 Bibliographic Format

SOURCE: DLF Digital Registry Working Group

SUMMARY: This paper proposes the definition of a subfield in field 538 to contain a URI intended to link to a description of technical details concerning how a digital resource was created.

KEYWORDS: Subfield $u, in field 538 (BD); System Details Note (BD); URI



12/16/02 - Made available to the MARC 21 community for discussion.

1/25/03 - Results of the MARC Advisory Committee discussion - Approved as amended. Participants agreed that the definition and scope of field 538 should be revised to allow for recording links to technical details relating to digital resources. Examples should also be added to the documentation. Participants agreed that field 538 should be defined in the holdings format to record copy-specific information for digital reproductions. It was also suggested that subfields $i (Display text) and $3 (Materials specified) be defined in the field for use with the display and identification of the materials described in subfield $u.

3/17/03 - Results of LC/NLC/BL review - Agreed with the MARBI decisions.

PROPOSAL No. 2003-02: Definition of subfield $u (URI) in Field 538 (System Details Note)


The Digital Library Federation (DLF) is working on defining requirements for and establishing a service that registers the existence of persistent digitally reformatted and born digital monograph and serial publications. This registry service would allow for sharing information between institutions about resources that have been digitized, where they can be accessed, and the specifications followed in their digitization so that an institution may determine if it was done at an adequate level for its long-term preservation needs. Such an effort could result in considerable savings for libraries in terms of redundant digitization, extension of valuable services in access to digital material, and could facilitate preservation decision making.

As part of the first phase of planning for the registry, a DLF Digital Registry Working Group has developed guidelines based on papers describing the functionality of the Digital Registry (see the DLF Registry of Digital Masters Web site). MARC 21 records for the digitized resources in the registry will utilize OCLC's current cataloging system. The guidelines detail the MARC 21 data elements that will be used to describe materials that an institution intends to digitize as well as born digital materials.


One of the elements considered essential is information concerning the technical standards used in creating the archival master copy. That information can be a description or a pointer to a description that is too lengthy to be included in the record itself. The DLF Digital Registry Functional requirements describe this piece of information as follows:

"a description or a pointer (such as a URL or a standard identifier) to a description of the technical standards used in creating the Master Copy (note that this is a key element - it is expected that materials will be digitized following many differing practices. In order for other institutions to rely on a master, they need to be satisfied that is of sufficient quality. The expectation is that there will be standard best practice guidelines created by the digital library community that libraries can simply "point" to via identifier or URL when appropriate...)"

The advantage of using a pointer is that the same standards may be used for a large number of resources and this would avoid inputting the information in many records. In addition the information may be quite extensive, so it would be better to link to the description rather than encode it.

Field 538 (System Details Note) is used for technical details about an item, such as the presence or absence of certain kinds of codes; or the physical characteristics of a computer file, such as recording densities, parity, blocking factors, mode of access, software programming language, computer requirements, etc. There is currently defined only subfield $a and the linking subfields $6 and $8. This field would be appropriate for such technical information as needed for the digital repository project. Subfield $u (Uniform resource identifier), if defined, would allow for linking to an external description of technical standards used.

Other fields that were considered were field 567 (Methodology Note), which is used for methodological characteristics, such as the algorithm, sampling procedures, or validation characteristics. Since this field concerns how the resource was assembled and has been specifically used for items such as case files, it did not seem as appropriate for the data.

Another field considered was field 583 (Action Note), which already has a subfield $u defined. Although it might be argued that the technical information might be considered relating to the action of preservation, the field may not be appropriate for the following reasons:


Subfield $u could be defined as follows:

$u - Uniform Resource Identifier (R)
Subfield $u contains the Uniform Resource Identifier (URI), for example, a URL or URN, which provides electronic access data in a standard syntax. In field 538, subfield $u is used to record the location of external or supplemental information accessible electronically that describes technical details about the creation and use of the digital resource.

As in other fields, subfield $u would be repeated only if both a URL and URN need to be recorded.

Subfield $a could be used to supply textual information about the URI link. The following is an example of an existing externally accessed description of technical standards followed in digitization of a print journal:

538 ## $aProject methodology for digital version $u


Define subfield $u (Uniform Resource Identifier) in Field 538 of the MARC 21 Bibliographic Format

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