NOTE: This is an historical document from a 1998 pilot project and
not a current Library of Congress metadata standard.
INTRODUCTION TO THE TABLE
Purpose: Identification of a core set of metadata elements to be used
in the development, testing, and implementation of multiple repositories.
Background: With a charter from the
Digital Futures Group at the Library of Congress, representatives
Library Services, ITS and the National Digital Library Program drafted
this list of elements drawing on previous work contained in Structural
Metadata Dictionary for LC Digitized Material, version 1.03,
Metadata Table for the Coolidge-Consumerism Experiment,
and on experience with the Thomson Editorial Asset Management System
(TEAMS) repository proof-of-concept project, December 1998-April 1999.
After broader discussion
and comment during summer 1999, some nomenclature was modified, elements
for audio-visual objects were added to the list and a distinction was
made between information necessary for digital preservation and for
digital reformatting. An application of the core metadata elements for
visual materials is currently in development as part of the Audio
Visual Preservation Digital Prototyping Project.
Types of Metadata: Metadata elements listed
in the table are categorized according to three types: descriptive,
administrative, and structural. Administrative metadata is used for
managing and preserving objects in the repository; structural metadata
is used primarily for storage of objects in a repository and for presentation;
descriptive metadata is used for discovery of objects. The elements
defined in this table are to support structural and administrative functions.
Functions served are access management, administration, discovery, persistent
identifier, presentation, digital preservation and preservation reformatting.
The Library intends to maintain the fullest descriptive metadata in
its main catalog. Experiences with the Coolidge-Consumerism experiment
and the TEAMS prototype, however, indicate that some descriptive information
is helpful for administration of metadata and presentation of content.
Consquently, five descriptive elements are included in the Table of
Core Metadata Elements.
Metadata Levels: A hierarchy of information
is proposed to accommodate the diversity of digital objects and to propagate
data with some efficiency. Metadata elements may be supplied at multiple
and various levels. Nesting of objects is expected and will be further
clarified during the pilot phase of metadata capture and deposit. Information
may be inherited from parent levels or may be specific to single objects
at a lower level. For example, a collection may have general access
rights but some of its items may be restricted. The access_rights attribute
value on the collection (set or aggregate level) may be "public," but
a single title(primary object level) in the collection may be "restricted."
The levels of metadata are
Table of Elements: The Table
of Core Metadata Elements for Library of Congress Digital Repository
Development is arranged in alphabetical order and includes the following
- Set - Set-level metadata applies to what is currently known
as a digital collection, e.g. Alexander Graham Bell Family Papers.
Digital collections are formed from aggregates that group digital
items by original content type, such as non-motion visual, text, motion
visual, or audio; and by custodial responsibility as well as by collection.
A collection may be determined from an archival series or from a topical
bibliography. Some digital collections are contained within a single
aggregate. Others are formed by numerous aggregates. Set-level metadata
applies to all aggregates within the set regardless of content or
- Aggregate - An aggregate organizes digital objects by digital
type and by digital custodial responsibility. A single aggregate may
be a digital collection. Aggregate-level metadata applies to all primary
objects within an aggregate.
- Primary Object - The specific item identified by the online
collection access aid as a coherent whole is known as the primary
object. Primary objects are usually the digital equivalents of physical
library items, such as a book, a sound recording, a movie, a single
title of sheet music, a folder of letters, a photograph, or a map.
This level metadata applies to all the intermediate and terminal objects
of a particular primary object.
- Intermediate Object - The intermediate object is
a view or component of the primary object. A book that can be presented
as page images or as searchable text has two intermediate objects.
One points to all the page images of the book, the other to an encoded
text file. Complex primary objects such as sound recordings offer
many intermediate object possibilities. Multiple sides or tracks for
a recording, each with sound and label components, may be captured
in several formats. A single78 rpm record with two sides will have
several audio files in both streaming and higher resolution formats,
as well as the image and text of the label for each side and the jacket
or album cover. Metadata for an intermediate object allows the
gathering of digital files and metadata for the creation of presentations.
- Terminal Object - The terminal object is the digital content
file or files that form the object. There is at least one terminal
for each object. Terminal object-level metadata is primarily structural
supplying the digital attributes of each file such as size, extension,
Example Records: An example
of data gathered for a letter from the Alexander
Graham Bell Family Papers online collection shows metadata that is
readily available for objects currently created, stored and delivered
through the American Memory interface
at the Library of Congress. Values entered into the table are examples
of the type of information that could appear in the field. Actual data
types and value tables will be defined and refined as part of several
pilot projects initiated in autumn 1999.
- Name is the label for the metadata element. Names
are intended to be easily comprehended and unambiguous.
- Definition is a brief description of the information
contained in the element.
- Function is an indicator of how the element is used.
Functions served by metadata elements are access management, administration,
discovery, persistent identifier, presentation, digital preservation
and preservation reformatting. Preservation (D) signifies digital
preservation and preservation (R) indicates preservation reformatting.
- Type is an indicator of the functions the metadata
is intended to support.
- Use is an indicator of frequency and requirement
of the element.
- Level is an indicator of position within the repository
hierarchy that the element is meaningful.
of Core Metadata Elements | Example
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September 8, 2005