Dublin Core Qualifiers
Jon Knight, and
Martin Hamilton
ROADS Project,
Department of Computer Studies,
Loughborough University.
Contents
The Dublin Core
proposal for metadata contains fifteen basic elements. These fifteen
elements are intended to cover most of the metadata attributes
that are needed to give a simple description of document like objects.
However with only fifteen elements there is often a need to supply
multiple values for each element. These different values need to be
differentiated from one another.
This differentiation is provided by the use of qualifiers.
Qualifiers have an identifier and a value and serve to inform users
and programs how to interpret the value in the element proper. For
example, one Dublin Core element is called Subject which has a
qualifier called Scheme. The Scheme tells us what
context we should interpret the value of the Subject in; it
might be an uncontrolled keyword, a Dewey Decimal Classification number,
a UDC number, a Library of Congress Subject Heading, etc, etc. Without
the qualifier we could not distinguish between one type of
Subject value and another.
This document is intended to provide an initial set of standard
qualifier names and values for use in Dublin Core metadata sets. The
reason for wanting a standard set of qualifier names and values is
that it makes it easier for programs to automatically process and
understand the qualifiers and thus the values of the elements.
In the following section, each element is described, followed by the
proposed standard qualifiers and qualifier values. It is also
proposed every element can have locally defined qualifiers with names
starting with "x-" whose values and effects upon the interpretation of the
element's value are only known to consenting groups of metadata users.
This type of extension mechanism is common in other Internet standards
such as RFC 822 mail headers and MIME Content-Types. Note also that the
qualifier names should normally be case insensitive, unless a
particular concrete representation of the Dublin Core Element Set
specifically requires case sensitivity.
There exist a small class of qualifiers that are applicable to many of
the Dublin Core elements and whose interpretation does not alter between
elements. These are:
- Language
- This qualifier provides an indication of the language that the
element value is written in (not the resource being
described; that is the purpose of the Language element itself).
The value of this qualifier should be a two or three character
language code from the ISO 639 standard. The default if this
qualifier is not present is English.
- Charset
- This qualifier provides an indication of the character set that
the element value is encoded with. Possible values are:
- ISO.8859-1
- ISO.8859-2
- ISO.8859-3
- ISO.8859-4
- ISO.8859-5
- ISO.8859-6
- ISO.8859-7
- ISO.8859-8
- ISO.8859-9
- UTF-8
The default if this qualifier is not present is ISO.8859-1 (a
superset of US ASCII suitable for Western languages and the default used
in WWW browsers).
This element is the name of the object that the Dublin Core metadata
relates to as given by the Creator or Publisher.
qualifiers and values:
- Scheme
- Internal
- The information provided is not part of an external coding system and
the coding should be qualified by an accompanying TYPE from the list below.
This is the default scheme value if the scheme is not explicitly stated.
- AACR2
- The title obeys the AACR2 cataloguing rules. The TYPE attribute
must be specified to indicate if the title is the main, continued,
spine, translated, etc.
- Type
- Main
- The main title of the work. This is the default type value if the
type is not explicitly stated.
- Long
- The long form of the work's title.
- The full form of the work's title (probably synonymous with Long).
- Short
- The short form of the title of the work.
- Alternative
- The alternative form of the title of the work.
- Subtitle
- The subtitle of the work.
- PartTitle
- The title of part of the work.
- Spine
- The title as it appears on a (printed) spine.
- Translated
- A translation of the title.
This Dublin Core element holds the subject descriptor or a set of keywords
that describe the contents of the object.
qualifiers and values:
- Scheme
- Internal
- The information provided is not part of an external coding system and
the coding should be qualified by an accompanying TYPE from the list below.
This is the default scheme value if the scheme is not explicitly stated.
- LCSH
- Library of Congress Subject Heading.
- UDC
- Universal Decimal Classification.
- DDC
- Dewey Decimal Classification.
- NLM
- National Library of Medicine.
- MeSH
- Medical Subject Headings.
- Colon
- Colon Classification.
- JEL
- Journal of Economic Literature Classification
- RCHME
- RCHME/English Heritage Thesaurus (ISBN 1-873592-20-5)
- AAT
- Art & Architecture Thesaurus
- ULAN
- Union List of Artist's Names
- TGN
- Thesaurus of Geographic Names
- ICONCLASS
- ICONCLASS
- SHIC2
- Social History & Industrial Classification
- TGM1
- LC Thesaurus for Graphic Materials I: Subject Terms
- MSC
- Mathematical Science Classification
- YKL
- Finnish Public Library Classification
- SAB
- Swedish Library Classification
- Type
- Keyword
- A simple, unconstrained list of comma separated keywords and/or
keyphrases. This is the default type value if the type is not
explicitly stated.
- Notes
- Miscellaneous notes about the resource, such as revision histories.
The Description element contains a textual description of the content
of the resource, including abstracts in the case of document-like
objects or content descriptions in the case of visual resources.
Future metadata collections might well include computational content
description (spectral analysis of a visual resource, for example) that
may not be embeddable in current network systems. In such a case this
field might contain a link to such a description rather than the
description itself.
qualifiers and values:
- Scheme
- Internal
- The information provided is not part of an external coding system and
the coding should be qualified by an accompanying TYPE from the list below.
This is the default scheme value if the scheme is not explicitly stated.
- URL
- The value of this element is a Uniform Resource Locator pointing
at an external representation of the description of the resource.
- URN
- The value of this element is a Uniform Resource Name identifying
an external representation of the description of the resource.
- Type
- Freetext
- A brief, freetext description of the resource provided by a
third party (such as a cataloguer). This is a the default if a TYPE is
not specified.
- Abstract
- The abstract as provided by the creator/publisher of the resource.
This element provides information about the persons and/or organisations
responsible for the intellectual content of the object that the Dublin
Core metadata relates to.
qualifiers and values:
- Scheme
- Internal
- The information provided is not part of an external coding system and
the coding should be qualified by an accompanying TYPE from the list below.
This is the default scheme value if the scheme is not explicitly stated.
- USMARC
- The information provided is a field from a USMARC record. It should
start with the field number, followed by the indicators and then any
sub-fields. Note that the subfield characters should be preceeded by
a "$" and the \x1F subfield delimiter from the Z39.2 record should be
excluded. For example:
1102 $aEFILA$cBrussels$d1996
- Type
- Name
- The name of the author. The name should conform to the BibTex
name construction rules. This is the default type value if the type
is not explicitly stated.
- Email
- The email address of the author.
- Postal
- The snail mail address of the author.
- Phone
- The telephone number of the author. This should be in the world
standard format of +Country-Code Area-Code Local-Number. For example
+44 1509 228237.
- Fax
- The fax number of the author. This should be in the world
standard format of +Country-Code Area-Code Local-Number. For example
+44 1509 228237.
- Affliation
- The instiution where the author is based.
- HomeEmail
- The author's home email address.
- HomePostal
- The author's home postal address.
- HomePhone
- The author's home phone number. This should be in the world
standard format of +Country-Code Area-Code Local-Number. For example
+44 1509 228237.
- HomeFax
- The author's home fax number. This should be in the world
standard format of +Country-Code Area-Code Local-Number. For example
+44 1509 228237.
- Homepage
- The URL of the author's homepage on the WWW.
- Keywords
- A list of keywords for this author.
- Order
- Whether the author is the primary author or not. Valid values
are primary, secondary, unknown or a numeric
ordering. If this element is not supplied, assume that the value for
specific author is unknown.
This element provides information about the persons and/or organisations
responsible for the dissemination of the object that the Dublin Core
metadata relates to.
qualifiers and values:
- Scheme
- Internal
- The information provided is not part of an external coding system and
the coding should be qualified by an accompanying TYPE from the list below.
This is the default scheme value if the scheme is not explicitly stated.
- USMARC
- The information provided is a field from a USMARC record. It should
start with the field number, followed by the field itself and then any
sub-fields.
- Type
- Name
- The name of the publisher. This is the default type value if the
type is not explicitly stated.
- Email
- The email address of the publisher.
- Postal
- The snail mail address of the publisher.
- Phone
- The telephone number of the publisher. This should be in the world
standard format of +Country-Code Area-Code Local-Number. For example
+44 1509 228237.
- Fax
- The fax number of the publisher. This should be in the world
standard format of +Country-Code Area-Code Local-Number. For example
+44 1509 228237.
- HomeEmail
- The publisher's home email address.
- HomePostal
- The publisher's home postal address.
- HomePhone
- The publisher's home phone number. This should be in the world
standard format of +Country-Code Area-Code Local-Number. For example
+44 1509 228237.
- HomeFax
- The publisher's home fax number. This should be in the world
standard format of +Country-Code Area-Code Local-Number. For example
+44 1509 228237.
- Homepage
- The URL of the publisher's homepage on the WWW.
- Keywords
- A list of keywords for this author.
This element provides information about other persons and/or
organisations involved in the production or distribution of the object
that the Dublin Core metadata relates to.
qualifiers and values:
- Scheme
- Internal
- The information provided is not part of an external coding system and
the coding should be qualified by an accompanying TYPE from the list below.
This is the default scheme value if the scheme is not explicitly stated.
- USMARC
- The information provided is a field from a USMARC record. It should
start with the field number, followed by the field itself and then any
sub-fields.
- Type
- Name
- The name of the agent. This is the default type if the type value
is not explicitly stated.
- Email
- The email address of the agent.
- Postal
- The snail mail address of the agent.
- Phone
- The telephone number of the agent. This should be in the world
standard format of +Country-Code Area-Code Local-Number. For example
+44 1509 228237.
- Fax
- The fax number of the agent. This should be in the world
standard format of +Country-Code Area-Code Local-Number. For example
+44 1509 228237.
- Affliation
- The instiution where the author is based.
- HomeEmail
- The other agent's home email address.
- HomePostal
- The other agent's home postal address.
- HomePhone
- The other agent's home phone number. This should be in the world
standard format of +Country-Code Area-Code Local-Number. For example
+44 1509 228237.
- HomeFax
- The other agent's home fax number. This should be in the world
standard format of +Country-Code Area-Code Local-Number. For example
+44 1509 228237.
- Homepage
- The URL of the other agent's homepage on the WWW.
- Keywords
- A list of keywords for this author.
- Role
- Editor
- This element relates to an editor of the resource.
- Illustrator
- This element relates to an illustrator of the resource.
- Binder
- This element relates to a binder of the resource.
- Translator
- This element relates to a translator of the resource.
- MachineReadableCreator
- This element relates to the agent responsible for the creation of
the machine-readable version of a resource.
- Sponsor
- This element relates to the agent who sponsers the resource.
- Compiler
- This element relates to the compiler of the resource.
- Funder
- This element relates to the funder of the resource.
- Composer
- This element relates to the composer of the resource.
- Cataloger
- This element relates to the cataloguer of the resource.
- Contact
- Agent to for end user to contact concerning this resource.
- Reviewer
- An agent who has reviewed this resource.
- Proofreader
- An agent who has proofread this resource.
This element holds the date of publication of the object
that the Dublin Core metadata relates to.
qualifiers and values:
- Scheme
- IETF.RFC-822
- Date conforms to the date formats described in RFC 822, for
example "Sat, 31 Aug 1996 21:12:34 +0100". This is the default scheme
value if the scheme is not explicitly stated.
- ANSI.X3.30-1985
- Date conforms to the date formats described in ANSI X3.30-1985.
For the A.D. era to December 31, 9999 YYYYMMDD is used; for example
19960831 (the same as FGDC?). It also defines other formats for
B.C. dates and A.D. after 9999.
- ISO.31-1:1992
- Date conforms to the date formats described in ISO 31-1:1992.
For example 1996-08-31.
- FGDC
- Date conforms to the date formats described in the FGDC. It is similar to the
ANSI.X3.30-1985 scheme; for example 19960831.
- SSE
- Seconds Since the Epoch; the standard UNIX internal time keeping
format. This is an integer number of seconds since midnight on 1st January
1970.
- Type
- Creation
- The date on which the resource was first created. This is the
default type value if the type is not explicitly stated.
- Current
- The date on which the current form of the resource was created.
- Modified
- The date on which the resource was last modified.
- ValidFrom
- The date from which the resource is valid.
- ValidTo
- The date after which the resource is no longer valid.
This element provides the facility to describe the genre of the
resource that the Dublin Core metadata was generated for.
qualifiers and values:
- Scheme
- DCObjects
- The element value is one of the values described in the Dublin Core Standard ObjectTypes
document. This is the default scheme value if the scheme is not
explicitly stated.
- Freetext
- The element value is a free text description of the genre.
- Type
This element holds the type of the object that the Dublin Core
metedata relates to.
qualifiers and values:
- Scheme
- IMT
- An Internet Media Type (aka MIME type). This is the default
scheme value if the scheme is not explicitly stated.
- MIME
- A synonym for IMT.
- Freetext
- A freetext description of the format of the resource.
- Type
The Identifier element in Dublin Core provides a way of identifying the
object that the metadata relates to.
qualifiers and values:
- Scheme
- URL
- A Uniform Resource Locator (URL) for the resource. This is the
default scheme value if the scheme is not explicitly stated.
- URN
- A Uniform Resource Name (URN) for the resource.
- ISBN
- International Standard Book Number for the resource (this is likely
to be included inside URNs in the future).
- ISSN
- International Standard Serial Number for the resource (this is likely
to be included inside URNs in the future).
- FPI
- Formal Public Identifier for the resource (this is likely to be
included inside URNs in the future).
- SICI
- Serial article identifier (picks out a single article in a journal
whereas ISSN just identifies the journal as a whole).
- Version
- A version number for this resource.
- Type
- Primary
- This identifier points to the primary (canonical) version of the
resource. This is the default type value if the type is not explicitly
stated.
- Copy
- This identifier points to a copy of the primary (canonical) version
of the resource.
This element is intented to describe relationships between the resource
that this set of Dublin Core metadata is concerned with and other
resources.
qualifiers and values:
- Scheme
- URL
- The related resource is being identified by its Uniform Resource
Locator (URL). This is the default identifier/scheme value if the
identifier/scheme is not explicitly stated.
- URN
- The related resource is being identified by its Uniform Resource
Name (URN).
- ISBN
- The related resource is being identified by its International
Standard Book Number (ISBN).
- ISSN
- The related resource is being identified by its International
Standard Serial Number (ISSN).
- FPI
- The related resoure is being identified by its Formal Public
Identifier (FPI).
- Type
- IsParentOf
- The resource being described by this set of Dublin Core metadata
is higher in some arbitrary hierarchy than the resource being pointed
to by this Relation element. This is the default type value if the
type is not explicitly stated.
- IsChildOf
- The resource being described by this set of Dublin Core metadata
is lower in some arbitrary hierarchy than the resource being pointed
to by this Relation element.
- IsMemberOf
- The resource being described by this set of Dublin Core metadata
is a member of a group of works whose entry point or overall identifier
is provided by this Relation element.
- IsDerivedFrom
- The resource being described by this set of Dublin Core metadata
is derived from the resource being pointed to by this Relation element.
- HasBibliographicInfoIn
- The resource being pointed to by this relation provides bibliographic
information for the main resource.
- IsRevisionHistoryFor
- The resource being pointed to by this relation provides a history of
revisions made to the main resource which the Dublin Core metadata was
created for.
- IsCriticalReviewOf
- The resource being pointed to by this relation provides a review of
the resource being described by the Dublin Core metadata.
- IsOverviewOf
- The resource being described by the Dublin Core metadata is overviewed
in the resource pointed to by this relation.
- IsContentRatingFor
- The resource pointed to by this relation is a set of content ratings for
the resource being described by the Dublin Core metadata.
- IsTermsAndConditionsFor
- The terms and conditions for access to the resource described by this
set of Dublin Core metadata are outlined in the resource pointed to by this
relation.
- IsDataFor
- Provides dataset or programs for another resource.
The source element in the Dublin Core is really a special case of the
Relation element. It is intended to provide a means of indicating the
provenance of the work that the Dublin Core metadata applies to. Note
that the Source element is intended to identify other objects that have
the same intellectual content as the resource being described by the DC
metadata, while the Relation element is intended to identify objects of
different intellectual content to which the resource is logically
connected.
qualifiers and values:
- Scheme
- Freetext
- A textual description of the source of the resource. This is the
default scheme value if the scheme is not explicitly stated.
- URL
- The source of the resource is being identified by its Uniform Resource
Locator (URL).
- URN
- The source of the resource is being identified by its Uniform Resource
Name (URN).
- ISBN
- The source of the resource is being identified by its International
Standard Book Number (ISBN).
- ISSN
- The source of the resource is being identified by its International
Standard Serial Number (ISSN).
- FPI
- The source of the resoure is being identified by its Formal Public
Identifier (FPI).
- Type
This element in the Dublin Core identifies the language in which the
resource is written.
qualifiers and values:
- Scheme
- Freetext
- A human readable name of the language. This is the default scheme value
if the scheme is not explicitly stated.
- Z3953
- The element value is a three character language code from the
Z39.53
coding set for written languages.
- ISO.639
- The element value is a two or three character language code from the
ISO 639 standard.
- Computer
- The element value is the name of a computer language.
- Type
The Coverage element of the Dublin Core Element Set is intended to
convey information about spatial and temporal coverage of the resource.
qualifiers and values:
- Scheme
- LatLong
- This qualifier specifies a latitude and longtitude. It is only
valid when used in conjunction the "Spatial" Type qualifier and so if
it is specified with no Type qualifier, it should be assumed that the
Type is "Spatial". The format of a "LatLong" element is the
latitude, followed by a "/" and then a longitude. For latitude
"+" is north of the equator and "-" is south of the equator. For
longitude "+" is west of the Greenwich meridian and "-" is east of the
Greenwich meridian. An example value for an element with this
qualifier is "-37.24.43/+121.58.54".
- OSGB
- This qualifier specifies an Ordnance Survey National Grid
Reference, based upon the national grid defined by Ordnance Survey of
Great Britain (OSGB). It is only valid when used in conjunction with
the "Spatial" TYPE qualifier. The format of an "OSGB" element is the
easting (distance East of NGR 000000 000000) a space " " and then the
northing (distance North of NGR 000000 000000). All "OSGB" elements
should be expressed with a six digit easting and six digit northing,
providing a reference precise to 1 metre. Greater precision is
optionally gained by the use of up to two digits following a decimal
point ("."), providing precision down to 1 centimetre. For example,
432760 345743 may optionally be expressed (where sufficient data are
available) as 432760.34 345743.22. Where data precise to one metre or
greater are not available, the reference should be padded with zeroes
("0") to maintain the six digit easting and northing -- 343 453 being
represented as 343000 453000, for example. OSGB 100km square letter
codes (SE, TQ etc) should be converted to the appropriate numeric
codes IN ALL CASES.
- ANSI.X3.30-1985
- This qualifier specifies a date/time range in a format specified in
ANSI X3.30-1985 standard. It is only valid when used in conjunction the
"Temporal" Type qualifier and so if it is specified with no Type
qualifier, it should be assumed that the Type is "Temporal".
- Freetext
- A textual description of the coverage of the resource. This is the
default scheme value if the scheme is not explicitly stated. For example
"19th century France", "Italy during the Reformation" or "The United
Kingdom of Great Britain and Northern Ireland".
- Type
- Spatial
- The element value describes some sort of spatial information from
the set described by the Scheme qualifier.
- Temporal
- The element value describes some sort of temporal information from
the set described by the Scheme qualifier.
The content of this element is intended to be a link (a URL or
other suitable URI as appropriate) to a copyright notice, a
rights-management statement, or perhaps a server that would
provide such information in a dynamic way. The intent of
specifying this field is to allow providers a means to associate
terms and conditions or copyright statements with a resource or
collection of resources. No assumptions should be made by users
if such a field is empty or not present.
qualifiers and values:
- Scheme
- Freetext
- A textual description of the copyright information for the resource.
This is the default scheme value if the scheme is not explicitly stated.
- URL
- A Uniform Resource Locator (URL) pointing to the copyright
information for the resource.
- URN
- A Uniform Resource Name (URN) identifying the copyright information
for the resource.
- Type
Many thanks to Terry Allen, Hans J. Becker, Dave Beckett, Dan Brickley,
Ron Daniel, Tony Gill, Ian Hamilton, Rachel Heery, Renato Iannella,
Thomas Krichel, Traugott Koch, Eric Miller, Paul Miller, Judith Pluemer,
Andy Powell, Roland Schwaenzl and Wolfram Sperber for comments made on
earlier versions of this document. This work was supported by a grant
from the UK Electronic Libraries
Programme (eLib).
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