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DATE: Dec. 16, 2005

NAME: Standardized terminology for access restrictions in field 506 of the MARC21 Bibliographic Format

SOURCE: DLF/OCLC Digital Registry Working Group

SUMMARY: This paper proposes a method for providing access restrictions using standardized terminology suitable for retrieval or reporting in Field 506 (Restrictions on Access Note) of the MARC 21 Bibliographic Format. It also proposes defining the field in the MARC 21 Holdings Format

KEYWORDS: Field 506 (BD,HD); Subfield $2, in field 506 (BD,HD); Restrictions on Access Note; Subfield $f, in field 506 (BD,HD)



12/16/05 - Made available to the MARC 21 community for discussion.

01/22/06 - Results of the MARC Advisory Committee discussion - Approved as amended. The definition of subfield $f was revised to say that it contains data from a standardized list, rather than "a term or phrase".

03/07/06 - Results of LC/LAC/BL review - Approved

PROPOSAL NO. 2006-03: Standardized terminology for access restrictions in field 506


A Registry of Digital Masters was defined by the Digital Library Federation in a set of functional requirement documents in 2001, and since then DLF members have worked with OCLC to implement such a registry by defining required information to be added to MARC 21 records. The Registry became available in 2004 and is gradually being populated. Among the original tenets of the Registry was that a registering institution must be committed to preserving the digital object for the long term and that a digital copy must be publicly available, although the public copy need not necessarily be free. The Registry is also required to make its records available for harvesting, to facilitate their inclusion in local catalogs or in free or fee-based discovery services.

It has become clear that some constituencies will only be interested in records for materials that have free public copies, while others will want to track all digital materials, even if there are fees involved or if a single resource can only be accessed as part of large licensed set. The advent of large scale digitization efforts such as the Google Library Project is resulting in digital masters being created of in-copyright material for which access copies may be unavailable for years to come. In the hope of serving both digital preservation and digital access communities, Digital Registry participants recently agreed to broaden the scope of the registry by allowing records for digital materials without access copies, provided that registry records carry clear, machine-identifiable indications of when access is open to the public or restricted, whether restricted to a limited user group, for a period of time, or indefinitely. Such indications could be used to select subsets of the Registry as needed for various systems and services. It might also be useful in other contexts, for example metadata harvesting, where only records describing resources freely available are in scope for a given service or system.


In order to enable the Registry to be "sliced and diced" into appropriate sets of records for different uses, there must be a place to put standardized terminology or coded values characterizing restrictions on access.

Fixed fields, while attractive from a control standpoint, are not appropriate because the information might apply to a particular copy or volume.

Field 506, Restrictions on Access Note, is already being used for free-form information about terms governing access, with additional subfields such as who or what imposes the restrictions, classes of authorized users, and arrangements for access. The field includes a $u (URI), $3 (Materials specified), and $5 (Institution to which field applies).

Field 506 is currently defined as follows:


Adding a subfield for standardized terminology plus a corresponding subfield $2 to identify the vocabulary from which the term was drawn would fulfill the needed function, require little effort to implement, and provide flexibility for different communities of interest to define their own lists of standardized terms. This would be an optional subfield, although the DLF Registry may decide to require it in its record guidelines.

The DLF Registry of Digital Masters Working Group suggested some possible values for a controlled list of access terms:

Note that this is a proposed list which has not yet been fully discussed, but is intended to serve as an example.

Field 506 is sometimes used to affirm that materials are available without restrictions, as it will be for some materials in the Registry of Digital Masters. In some systems, the presence of a 506 field is taken to imply that the material is restricted. It would be useful to have a machine-actionable distinction between 506 fields that state restrictions and those that state the absence of restrictions. Both indicators of the 506 are currently undefined. Defining one to indicate whether the field indicates restrictions would be useful in providing a high-level binary Open vs. Restricted flag that would be easier and more reliable for machine processing.

Examples with additions as specified in Section 3:

506 # # $aAccess copy available to the general public.$fUnrestricted$2[code for access term list]$5MH

506 # # $a Access restricted to users with a valid Harvard ID.$fLicense$2[code for access term list]$5MH

Finally, restrictions on access more appropriately apply to holdings or copies. MARC21 should support the ability to associate a restriction not only with an institution, but with the holding to which it applies. The 506 should be added to the Holdings Format, joining similar fields such as 541, 561, 562, and 563.


In field 506 (Restrictions on Access Note) in the MARC 21 Bibliographic format:

In the MARC 21 Holdings format:


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