Dublin Core Collection Description
Proposed Term : Accrual Periodicity

Dublin Core Collection Description Working Group
Date Issued:
Is Replaced By:
Not applicable
Latest Version:
Status of Document:
This is a DCMI Working Draft.
Description of Document: This document presents a proposal from the Dublin Core Collection Description Working Group for a new domain-specific element, accrualPeriodicity.


The Dublin Core Collection Description Working Group is developing a a Dublin Core Application Profile (DCAP) for collection-level description, i.e. for the description of a collection itself as a resource, rather than the description of each of the individual items that make up that collection. The work adopts a broad definition of a collection and is seeking to develop a schema which is applicable to a wide range of collections.

One of the requirements is to provide information about whether and how items are added to a collection. Such information can provide indications of the significance and the currency of a collection. Three distinct but related categories of information have been identified:

While these attributes are related, they are sufficiently distinct to be represented using three separate properties that can be used to make distinct statements about the collection.

No existing properties in the DCMI vocabularies support the capture of this information. It is not covered by dc:description since this information deals with the process of adding items, rather than with the content of the collection (or of the items within the collection.

Accrual Periodicity

This property allows statements to be made about how frequently items are added to the collection.

This property supports searches of the form

Find collections that have an Accrual Periodicity corresponding to a specified value (e.g. Annual)

It also allows a user to obtain a value for Accrual Periodicity for a known collection, or to compare values for collections that have been discovered according to some other criteria.

Furthermore, the use of a vocabulary encoding scheme provides a list of unambiguous values for the property, and supports the construction of precise operations on metadata using this property. The property could be used with other encoding schemes or with free text values.


Name accrualPeriodicity
Label Accrual Periodicity
Definition The frequency with which items are added to a collection.
Comment Recommended best practice is to use a value from the DCCD Accrual Periodicity encoding scheme.

The Accrual Periodicity for a serial:

Monthly [Encoding scheme = (Proposed) DCCD Accrual Periodicity]

The Accrual Periodicity for a special collection to which items are added at unpredictable intervals:

Completely irregular [Encoding scheme = (Proposed) DCCD Accrual Periodicity]

The Accrual Periodicity for a catalogue for which new metadata records are being added continuously:

Continuously updated [Encoding scheme = (Proposed) DCCD Accrual Periodicity]

Type of term Element
Term qualified [n/a]
Why needed

Information about the frequency with which items are being added to a collection helps a user to find a collection. Specifically this property will support searches of the form:

Which collections have Accrual Periodicity of "Monthly"?

Which Accrual Periodicities are in use for collections with Accrual Method of "License"?


Perhaps more importantly, it allows a user to select from amongst a number of candidate collections, and/or to compare this attribute of collections that are otherwise similar.

It also helps a user to interpret a collection that they have found or selected by some other criteria.

Working Group support

See the mailing list archives of the WG, especially Jul 2004.

Proposed status Conforming
Related DCMI terms


Related non-DCMI terms

(Proposed encoding scheme) DCCDAccrualPeriodicity
See http://www.ukoln.ac.uk/metadata/dcmi/collection-DCCDAccrualPeriodicity/

(Proposed element) accrualMethod
See http://www.ukoln.ac.uk/metadata/dcmi/collection-accrualMethod/

(Proposed element) accrualPolicy
See http://www.ukoln.ac.uk/metadata/dcmi/collection-accrualPolicy/

The International Standard for Archival Description (ISAD(G)), Second Edition (2000) is a descriptive standard for archival records. It can be applied to units of description at any level from the collection (or fonds) to the individual item, and includes a related element:

  • 3.3.3 Accruals

    Purpose: To inform the user of foreseen additions to the unit of description.

    Rules: Indicate if accruals are expected. Where appropriate, give an estimate of their quantity and frequency.

ISAD(G) does not itself provide a machine-readable binding.

The Encoded Archival Description (EAD) DTD is a standard for encoding archival finding aids using SGML or XML. It includes an XML element:

  • <accruals> Accruals

    Information about anticipated additions to the materials being described. Can indicate quantity and frequency. Can also be used to indicate that no additions are expected.

This is an XML element, not an RDF property.

Impact on applications

If existing DC applications for collection-level description capture this data, they probably do so as part of the value of a dc:description element. Strictly speaking this information is probably not part of "an account of the content of the resource", and the use of dc:description in this way does not conform to the semantics of that property - and for this reason the proposal is for an element rather than an element refinement of dc:description.

The introduction of a distinct property allows the metadata creator to represent this information separately from the description of the scope and content of the collection. As the property is not proposed as a refinement of one of the 15 DC elements available in the "Simple DC" application profile, the information represented by this proposed property will be lost during "dumb-down" to "Simple DC".

About the proposers

The term is proposed by the Dublin Core Collection Description Working Group. One of the primary aims of the WG is the development of a Dublin Core Application Profile (DCAP) for collection-level description, i.e. for the description of a collection as a resource, rather than the description of the individual items that make up that collection.

Records of the activity of the WG are available in the mailing list archives.

The current draft of the Collection Description Application Profile is available at http://www.ukoln.ac.uk/metadata/dcmi/collection-application-profile/

Changes made in this version

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Metadata associated with this resource: http://dublincore.org/documents/collection-accrualPeriodicity/index.shtml.rdf