RDF Terminology and Concepts

12 January 2001
Graham Klyne
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.


The RDF Model and Syntax Specification.
Data describing Web resources [RDFM&S].
Web Resource:
Anything that is identified by a URI [RFC2396].
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.]]]
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.
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.
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)
An environment within which some statements are taken to be true.
A reference to a statement without necessarily making any assertion about its truth or falsity.
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.
[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.



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/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...


Insightful comments were provided by Pierre-Antoine Champin.