RDF Terminology and Concepts

Revised:

12 January 2001

Editor:

Graham Klyne

Contributors:

Graham Klyne

Brian McBride

Bill dehOra

Dan Brickley

This is currently a live working document, being a collection of suggestions from participants in the W3C RDF Interest Group.

Terminology

RDFM&S, M&S:

The RDF Model and Syntax Specification.

Metadata:

Data describing Web resources [RDFM&S].

Web Resource:

Anything that is identified by a URI [RFC2396].

Entity:

Anything which exists or has existed. Note that RFC2396 uses this term in a more restricted sense, to mean some data represents some aspect of a Web Resource.

RDF Resource:

[See RDF M&S section 5] Note that an RDF resource is not necessarily a web resource, though any web resource can be an RDF resource.

Consider: http://foo.com/#a and http://foo.com/#b may name distinct RDF resources, but if used to access web resources they both refer to the common web resource http://foo.com/

[[[This distinction between "Web resource" and "RDF Resource" is not a desired outcome, but an interpretation of different uses of the term "resource" in different documents.]]]

Resource:

May refer to an RDF resource or a Web Resource. Some resources may be both. In discussion of RDF, this term is often used to mean RDF Resource.

RDF Resource Identifier, Resource Identifier:

A URI plus optional anchor ID.[RDFM&S]

RDF Resource Identifiers are understood to name RDF Resources.

RDF Statement, Statement:

[See RDFM&S section 5]

RDF Description:

[See RDFM&S] Construct containing representations of a number of RDF statements about a specific RDF resource, and possibly some additional statements.

Referent:

The entity or concept that an RDF Resource describes. [RDFM&S]

Distributive Referent:

A Referent that describes each of the Resources in a container, not including the container. The Referent is said to be made on the container. [RDFM&S]

Description [of]:

(As opposed to RDF Description) Language or data structure providing information about some entity or concept.

Stand for:

The use of one entity or concept in a description to refer to some other entity or concept. For example, "X stands for Y in Z" meaning that occurrences of "X" in "Z" are to be understood as references to "Y".

Reification (of a statement):

[See RDFM&S section 5] A resource that stands for the statement together with the four statements that describe the statement. More than one reification may exist for a given statement.

(There is some debate whether multiple reifications of a statement are necessarily equivalent.)

Reified Statement:

[See RDFM&S section 5] A resource that stands for a statement in a Reification. This resource has four properties describing the statement, and maybe others.

Reification Quad:

The four statements that make up a Reification.

Representation:

A data structure (abstract or concrete) that captures some essential properties of some entity or concept.

Representing [x]:

Being a representation of [x] (see above)

Context:

An environment within which some statements are taken to be true.

Quoting:

A reference to a statement without necessarily making any assertion about its truth or falsity.

Stating:

The expression of an RDF statement [or set of statements] in some context of discourse that is taken to be an assertion of the truth of the statement[s] in that context.

Model:

[See RDFM&S section 5].

This term is used in three distinct ways:

(a) The RDF Model, meaning the underlying structure and interpretation of RDF data

(b) An RDF Model, meaning a collection of RDF statements

(c) Logical Model, being a formal logicians term with quite specific meaning. (see http://www-rci.rutgers.edu/~cfs/305_html/Deduction/FormalSystemDefs.html).

(This term has caused some confusion, since it has a quite specific meaning to logicians, which is not the same as some would regard as its "natural" meaning.)

RDF Graph:

A set of RDF Statements.

Reification of an RDF Graph:

A (bag/collection?) containing the reifications of the statements in an RDF Graph

Reified Graph:

The (bag/collection?) in the reification of an RDF graph.

Higher Order Statement:

A Statement whose Referent is another Statement.[RDFM&S]

Higher Order Context:

A Context whose Referent is another Context.

Concepts

[[[TBD]]]

Additional resources

Some related resources / context:

http://www.w3.org/Help/siteindex W3C site index / technology keywords

http://www.w3.org/People/Berners-Lee/Weaving/glossary.html Glossary from 'Weaving the Web'.

http://www.w3.org/WCA/ Web Characterisation Initiative (historical interest)

http://www.w3.org/1999/05/WCA-terms/ Web Characterization Terminology & Definitions Sheet W3C Working Draft 24-May-1999 HTTP-NG Activity Statement (historical interest)

http://www.w3.org/Protocols/HTTP-NG/Activity.html

http://www.w3.org/TR/WD-HTTP-NG-interfaces/ HTTP-NG Web Interfaces (an attempt to formalise our a notion of URIs, resources etc in terms of a distributed object type hierarchy).

http://www.w3.org/Addressing/ Naming and Addressing: URIs, URLs, ...

http://www.ietf.org/rfc/rfc2396.txt -- URIs

http://www.w3.org/Protocols/rfc2616/rfc2616.html -- for HTTP 1.1's notion of URI, 'resource', entity etc...

Acknowledgements

Insightful comments were provided by Pierre-Antoine Champin.

References

[RDFM&S]

[RFC2396]

[[[TBD]]]