RDF 1.2 Schema (original) (raw)

RDF Schema provides a data-modelling vocabulary for RDF data. RDF Schema is an extension of the basic RDF vocabulary.

This document is an edited version of the 2014 RDF Schema Recommendation. The purpose of this revision is to make this document available as part of the RDF 1.2 document set. Changes are limited to errata, revised references, terminology updates, and adaptations to the introduction. The title of the document was changed from [[[RDF11-SCHEMA]]] to RDF 1.2 Schema. The technical content of the document is unchanged. Details of the changes are listed in the Changes section. Since the edits to this document do not constitute a technical change the Director decided no new implementation report was required.

Introduction

RDF Schema provides a data-modelling vocabulary for RDF data. It is complemented by several companion documents which describe the basic concepts and abstract syntax of RDF [[RDF12-CONCEPTS]], the formal semantics of RDF [[RDF12-SEMANTICS]], and various concrete syntaxes for RDF, such as Turtle [[RDF12-TURTLE]], TriG, [[RDF12-TRIG]], and JSON-LD [[JSON-LD11]]. The RDF Primer [[RDF12-PRIMER]] provides an informal introduction and examples of the use of the concepts specified in this document.

This document is intended to provide a clear specification of RDF Schema to those who find the formal semantics specification [[RDF12-SEMANTICS]] daunting. Thus, this document duplicates material also specified in the RDF Semantics specification. Where there is disagreement between this document and the RDF Semantics specification, the RDF Semantics specification should be taken to be correct.

RDF Schema is a semantic extension of RDF. It provides mechanisms for describing groups of related resources and the relationships between these resources. RDF Schema is written in RDF using the terms described in this document. These resources are used to determine characteristics of other resources, such as the domains and ranges of properties.

The RDF Schema class and property system is similar to the type systems of object-oriented programming languages such as Java. RDF Schema differs from many such systems in that instead of defining a class in terms of the properties its instances may have, RDF Schema describes properties in terms of the classes of resource to which they apply. This is the role of the domain and range mechanisms described in this specification. For example, we could define the eg:author property to have a domain of eg:Document and a range ofeg:Person, whereas a classical object oriented system might typically define a class eg:Book with an attribute calledeg:author of type eg:Person. Using the RDF approach, it is easy for others to subsequently define additional properties with a domain of eg:Document or a range ofeg:Person. This can be done without the need to re-define the original description of these classes. One benefit of the RDF property-centric approach is that it allows anyone to extend the description of existing resources, one of the architectural principles of the Web [[RDF-NOT]].

This specification does not attempt to enumerate all the possible forms of representing the meaning of RDF classes and properties. Instead, the RDF Schema strategy is to acknowledge that there are many techniques through which the meaning of classes and properties can be described. Richer vocabulary or 'ontology' languages such as OWL [[OWL2-OVERVIEW]], inference rule languages and other formalisms (for example temporal logics) will each contribute to our ability to capture meaningful generalizations about data in the Web.

The language defined in this specification consists of a collection of RDF resources that can be used to describe other RDF resources in application-specific RDF vocabularies. The core vocabulary is defined in a namespace informally called rdfs here. That namespace is identified by the IRI

http://www.w3.org/2000/01/rdf-schema#

and is conventionally associated with the prefix rdfs:. This specification also uses the prefixrdf: to refer to the RDF namespace

http://www.w3.org/1999/02/22-rdf-syntax-ns#

For convenience and readability, this specification uses an abbreviated form to represent IRIs. A name of the form prefix:suffix should be interpreted as a IRI consisting of the IRI associated with the prefix concatenated with the suffix.

Classes

Resources may be divided into groups called classes. The members of a class are known as instances of the class. Classes are themselves resources. They are often identified by IRIs and may be described using RDF properties. The rdf:type property may be used to state that a resource is an instance of a class.

RDF distinguishes between a class and the set of its instances. Associated with each class is a set, called the class extension of the class, which is the set of the instances of the class. Two classes may have the same set of instances but be different classes. For example, the tax office may define the class of people living at the same address as the editor of this document. The Post Office may define the class of people whose address has the same zip code as the address of the author. It is possible for these classes to have exactly the same instances, yet to have different properties. Only one of the classes has the property that it was defined by the tax office, and only the other has the property that it was defined by the Post Office.

A class may be a member of its own class extension and may be an instance of itself.

The group of resources that are RDF Schema classes is itself a class called rdfs:Class.

If a class C is a subclass of a class C', then all instances of C will also be instances of C'. The rdfs:subClassOf property may be used to state that one class is a subclass of another. The term super-class is used as the inverse of subclass. If a class C' is a super-class of a class C, then all instances of C are also instances of C'.

The RDF Concepts and Abstract Syntax [[RDF12-CONCEPTS]] specification defines the RDF concept of an RDF datatype. All datatypes are classes. The instances of a class that is a datatype are the members of the value space of the datatype.

rdfs:Resource

All things described by RDF are called resources, and are instances of the class rdfs:Resource. This is the class of everything. All other classes are subclasses of this class. rdfs:Resource is an instance of rdfs:Class.

rdfs:Class

This is the class of resources that are RDF classes.rdfs:Class is an instance of rdfs:Class.

rdfs:Literal

The class rdfs:Literal is the class of literal values such as strings and integers. Property values such as textual strings are examples of RDF literals.

rdfs:Literal is an instance of rdfs:Class.rdfs:Literal is a subclass of rdfs:Resource.

rdfs:Datatype

rdfs:Datatype is the class of datatypes. All instances ofrdfs:Datatype correspond to the RDF model of a datatype described in the RDF Concepts specification [[RDF12-CONCEPTS]].rdfs:Datatype is both an instance of and a subclass of rdfs:Class. Each instance of rdfs:Datatype is a subclass of rdfs:Literal.

rdf:langString

The class rdf:langString is the class oflanguage-tagged string values. rdf:langString is an instance ofrdfs:Datatype and a subclass of rdfs:Literal.

rdf:dirLangString

The class rdf:dirLangString is the class ofdirectional language-tagged string values. rdf:dirLangString is an instance ofrdfs:Datatype and a subclass of rdfs:Literal.

rdf:HTML

The class rdf:HTML is the class ofHTML literal values.rdf:HTML is an instance ofrdfs:Datatype and a subclass of rdfs:Literal.

rdf:XMLLiteral

The class rdf:XMLLiteral is the class ofXML literal values.rdf:XMLLiteral is an instance ofrdfs:Datatype and a subclass of rdfs:Literal.

rdf:JSON

The class rdf:JSON is the class ofJSON literal values.rdf:JSON is an instance ofrdfs:Datatype and a subclass of rdfs:Literal.

rdf:Property

rdf:Property is the class of RDF properties.rdf:Property is an instance of rdfs:Class.

rdf:Proposition

rdf:Proposition is the class of reified triples.rdf:Proposition is an instance of rdfs:Class.

Properties

The RDF Concepts and Abstract Syntax specification [[RDF12-CONCEPTS]] describes the concept of an RDF property as a relation between subject resources and object resources.

This specification defines the concept of subproperty. The rdfs:subPropertyOf property may be used to state that one property is a subproperty of another. If a property P is a subproperty of property P', then all pairs of resources which are related by P are also related by P'. The term super-property is often used as the inverse of subproperty. If a property P' is a super-property of a property P, then all pairs of resources which are related by P are also related by P'. This specification does not define a top property that is the super-property of all properties.

The basic facilities provided by rdfs:domain and rdfs:range do not provide any direct way to indicate property restrictions that are local to a class. Although it is possible to combine use rdfs:domain and rdfs:range with sub-property hierarchies, direct support for such declarations are provided by richer Web Ontology languages such as OWL [[OWL2-OVERVIEW]].

rdfs:range

rdfs:range is an instance of rdf:Property that is used to state that the values of a property are instances of one or more classes.

The triple

P rdfs:range C

states that P is an instance of the class rdf:Property, that C is an instance of the class rdfs:Class and that the resources denoted by the objects of triples whose predicate is P are instances of the class C.

Where P has more than one rdfs:range property, then the resources denoted by the objects of triples with predicate P are instances of all the classes stated by the rdfs:range properties.

The rdfs:range property can be applied to itself. Therdfs:range of rdfs:range is the class rdfs:Class. This states that any resource that is the value of an rdfs:range property is an instance of rdfs:Class.

The rdfs:range property is applied to properties. This can be represented in RDF using the rdfs:domain property. The rdfs:domain of rdfs:range is the class rdf:Property. This states that any resource with an rdfs:range property is an instance ofrdf:Property.

rdfs:domain

rdfs:domain is an instance of rdf:Property that is used to state that any resource that has a given property is an instance of one or more classes.

A triple of the form:

P rdfs:domain C

states that P is an instance of the class rdf:Property, that C is a instance of the class rdfs:Class and that the resources denoted by the subjects of triples whose predicate is P are instances of the class C.

Where a property P has more than one rdfs:domain property, then the resources denoted by subjects of triples with predicate P are instances of all the classes stated by the rdfs:domain properties.

The rdfs:domain property may be applied to itself. Therdfs:domain of rdfs:domain is the class rdf:Property. This states that any resource with an rdfs:domain property is an instance ofrdf:Property.

The rdfs:range ofrdfs:domain is the class rdfs:Class. This states that any resource that is the value of an rdfs:domain property is an instance of rdfs:Class.

rdf:type

rdf:type is an instance of rdf:Property that is used to state that a resource is an instance of a class.

A triple of the form:

R rdf:type C

states that C is an instance of rdfs:Class and R is an instance of C.

The rdfs:domain ofrdf:type is rdfs:Resource. The rdfs:range of rdf:type is rdfs:Class.

rdf:reifies

rdf:reifies is an instance of rdf:Property that is used to associate a resource (reifier) with a triple (proposition).

A triple of the form:

R rdf:reifies <<S P O>>

states that R is an instance of rdfs:Resource and reifies the triple term <<S P O>>, where S, P, and O represent the subject, predicate, and object of the reified triple, respectively. The object <<S P O>> is an instance of the class rdf:Proposition.

The rdfs:domain ofrdf:reifies is rdfs:Resource. The rdfs:range of rdf:reifies is rdf:Proposition.

rdfs:subClassOf

The property rdfs:subClassOf is an instance of rdf:Property that is used to state that all the instances of one class are instances of another.

A triple of the form:

C1 rdfs:subClassOf C2

states that C1 is an instance of rdfs:Class,C2 is an instance of rdfs:Class and C1 is a subclass of C2. The rdfs:subClassOf property is transitive.

The rdfs:domain ofrdfs:subClassOf is rdfs:Class. The rdfs:range of rdfs:subClassOf is rdfs:Class.

rdfs:subPropertyOf

The property rdfs:subPropertyOf is an instance of rdf:Property that is used to state that all resources related by one property are also related by another.

A triple of the form:

P1 rdfs:subPropertyOf P2

states that P1 is an instance of rdf:Property,P2 is an instance of rdf:Property and P1 is a subproperty of P2. Therdfs:subPropertyOf property is transitive.

The rdfs:domain ofrdfs:subPropertyOf is rdf:Property. The rdfs:range ofrdfs:subPropertyOf is rdf:Property.

rdfs:label

rdfs:label is an instance of rdf:Property that may be used to provide a human-readable version of a resource's name.

A triple of the form:

R rdfs:label L

states that L is a human readable label for R.

The rdfs:domain ofrdfs:label is rdfs:Resource. The rdfs:range of rdfs:label isrdfs:Literal.

Multilingual labels are supported using the language tagging facility of RDF literals.

Using the Domain and Range vocabulary

This specification introduces an RDF vocabulary for describing the meaningful use of properties and classes in RDF data. For example, an RDF vocabulary might describe limitations on the types of values that are appropriate for some property, or on the classes to which it makes sense to ascribe such properties.

RDF Schema provides a mechanism for describing this information, but does not say whether or how an application should use it. For example, while an RDF vocabulary can assert that an author property is used to indicate resources that are instances of the class Person, it does not say whether or how an application should act in processing that range information. Different applications will use this information in different ways. For example, data checking tools might use this to help discover errors in some data set, an interactive editor might suggest appropriate values, and a reasoning application might use it to infer additional information from instance data.

RDF vocabularies can describe relationships between vocabulary items from multiple independently developed vocabularies. Since IRIs are used to identify classes and properties on the Web, it is possible to create new properties that have a domain or range whose value is a class defined in another namespace.

Other vocabulary

Additional classes and properties, including constructs for representing containers and RDF statements, and for deploying RDF vocabulary descriptions in the World Wide Web, are defined in this section.

Container Classes and Properties

RDF containers are resources that are used to represent collections. The same resource may appear in a container more than once. Unlike containment in the physical world, a container may be contained in itself.

Three different kinds of container are defined. Whilst the formal semantics [[RDF12-SEMANTICS]] of all three classes of container are identical, different classes may be used to indicate informally further information. An rdf:Bag is used to indicate that the container is intended to be unordered. An rdf:Seq is used to indicate that the order indicated by the numerical order of the container membership properties of the container is intended to be significant. An rdf:Alt container is used to indicate that typical processing of the container will be to select one of the members.

Just as a hen house may have the property that it is made of wood, that does not mean that all the hens it contains are made of wood, a property of a container is not necessarily a property of all of its members.

RDF containers are defined by the following classes and properties.

rdfs:Container

The rdfs:Container class is a super-class of the RDF Container classes, i.e. rdf:Bag,rdf:Seq, rdf:Alt.

rdf:Bag

The rdf:Bag class is the class of RDF 'Bag' containers. It is a subclass of rdfs:Container. Whilst formally it is no different from an rdf:Seq or anrdf:Alt, the rdf:Bag class is used conventionally to indicate to a human reader that the container is intended to be unordered.

rdf:Seq

The rdf:Seq class is the class of RDF 'Sequence' containers. It is a subclass of rdfs:Container. Whilst formally it is no different from an rdf:Bag or anrdf:Alt, the rdf:Seq class is used conventionally to indicate to a human reader that the numerical ordering of the container membership properties of the container is intended to be significant.

rdf:Alt

The rdf:Alt class is the class of RDF 'Alternative' containers. It is a subclass of rdfs:Container. Whilst formally it is no different from an rdf:Seq or anrdf:Bag, the rdf:Alt class is used conventionally to indicate to a human reader that typical processing will be to select one of the members of the container. The first member of the container, i.e. the value of the rdf:_1 property, is the default choice.

rdfs:ContainerMembershipProperty

The rdfs:ContainerMembershipProperty class has as instances the properties rdf:_1, rdf:_2, rdf:_3 ... that are used to state that a resource is a member of a container.rdfs:ContainerMembershipProperty is a subclass of rdf:Property. Each instance ofrdfs:ContainerMembershipProperty is an rdfs:subPropertyOf the rdfs:member property.

Given a container C, a triple of the form:

C rdf:_nnn O

where nnn is the decimal representation of an integer greater than 0 with no leading zeros, states that O is a member of the container C.

Container membership properties may be applied to resources other than containers.

rdfs:member

rdfs:member is an instance of rdf:Property that is a super-property of all the container membership properties i.e. each container membership property has an rdfs:subPropertyOf relationship to the property rdfs:member.

The rdfs:domain ofrdfs:member is rdfs:Resource. The rdfs:range of rdfs:member isrdfs:Resource.

RDF Collections

RDF containers are open in the sense that the core RDF specifications define no mechanism to state that there are no more members. The RDF Collection vocabulary of classes and properties can describe a closed collection, i.e. one that can have no more members.

A collection is represented as a list of items, a representation that will be familiar to those with experience of Lisp and similar programming languages. There is a shorthand notation in the Turtle syntax specification for representing collections.

RDFS does not require that there be only one first element of a list-like structure, or even that a list-like structure have a first element.

rdf:List

rdf:List is an instance of rdfs:Class that can be used to build descriptions of lists and other list-like structures.

rdf:first

rdf:first is an instance of rdf:Property that can be used to build descriptions of lists and other list-like structures.

A triple of the form:

L rdf:first O

states that there is a first-element relationship between L and O.

The rdfs:domain of rdf:first is rdf:List. The rdfs:range of rdf:first is rdfs:Resource.

rdf:rest

rdf:rest is an instance of rdf:Property that can be used to build descriptions of lists and other list-like structures.

A triple of the form:

L rdf:rest O

states that there is a rest-of-list relationship between L and O.

The rdfs:domain of rdf:rest is rdf:List. The rdfs:range of rdf:rest is rdf:List.

rdf:nil

The resource rdf:nil is an instance of rdf:List that can be used to represent an empty list or other list-like structure.

A triple of the form:

L rdf:rest rdf:nil

states that L is an instance of rdf:List that has one item; that item can be indicated using the rdf:first property.

Reification Vocabulary

rdf:Statement

rdf:Statement is an instance of rdfs:Class. It is intended to represent the class of RDF statements. An RDF statement is the statement made by a token of an RDF triple. The subject of an RDF statement is the instance of rdfs:Resource identified by the subject of the triple. The predicate of an RDF statement is the instance of rdf:Resource identified by the predicate of the triple. The object of an RDF statement is the instance of rdfs:Resource identified by the object of the triple.rdf:Statement is in the domain of the properties rdf:predicate, rdf:subject and rdf:object. Different individual rdf:Statement instances may have the same values for their rdf:predicate,rdf:subject and rdf:object properties.

RDF statements are not triples in an RDF graph so their values for rdf:predicate do not need to be instances ofrdf:Property in that graph, although in most cases they will be.

rdf:subject

rdf:subject is an instance of rdf:Property that is used to state the subject of a statement.

A triple of the form:

S rdf:subject R

states that S is an instance of rdf:Statement and that the subject of S is R.

rdf:predicate

rdf:predicate is an instance of rdf:Property that is used to state the predicate of a statement.

A triple of the form:

S rdf:predicate P

states that S is an instance of rdf:Statement, that P is an instance ofrdfs:Resource and that the predicate of S is P.

The rdfs:domain ofrdf:predicate is rdf:Statement and the rdfs:range is rdfs:Resource.

rdf:object

rdf:object is an instance of rdf:Property that is used to state the object of a statement.

A triple of the form:

S rdf:object O

states that S is an instance of rdf:Statement and that the object of S isO.

The rdfs:domain ofrdf:object is rdf:Statement. The rdfs:range of rdf:object isrdfs:Resource.

Utility Properties

The following utility classes and properties are defined in the RDF core namespaces.

rdfs:seeAlso

rdfs:seeAlso is an instance of rdf:Property that is used to indicate a resource that might provide additional information about the subject resource.

A triple of the form:

S rdfs:seeAlso O

states that the resource O may provide additional information aboutS. It may be possible to retrieve representations of O from the Web, but this is not required. When such representations may be retrieved, no constraints are placed on the format of those representations.

The rdfs:domain ofrdfs:seeAlso is rdfs:Resource. The rdfs:range of rdfs:seeAlso isrdfs:Resource.

rdfs:isDefinedBy

rdfs:isDefinedBy is an instance of rdf:Property that is used to indicate a resource defining the subject resource. This property may be used to indicate an RDF vocabulary in which a resource is described.

A triple of the form:

S rdfs:isDefinedBy O

states that the resource O defines S. It may be possible to retrieve representations of O from the Web, but this is not required. When such representations may be retrieved, no constraints are placed on the format of those representations. rdfs:isDefinedBy is a subproperty of rdfs:seeAlso.

The rdfs:domain ofrdfs:isDefinedBy is rdfs:Resource. The rdfs:range of rdfs:isDefinedBy isrdfs:Resource.

rdf:value

rdf:value is an instance of rdf:Property that may be used in describing structured values.

rdf:value has no meaning on its own. It is provided as a piece of vocabulary that may be used in idioms such as illustrated in example below:

    <http://www.example.com/2002/04/products#item10245>
        <http://www.example.org/terms/weight> [
           rdf:value 2.4 ;
           <http://www.example.org/terms/units> <http://www.example.org/units/kilograms>
           ] .

Despite the lack of formal specification of the meaning of this property, there is value in defining it to encourage the use of a common idiom in examples of this kind.

The rdfs:domain ofrdf:value is rdfs:Resource. The rdfs:range of rdf:value is rdfs:Resource.

RDF Schema summary

The tables in this section provide an overview of the RDF Schema vocabulary.

RDF classes

Class name comment
rdfs:Resource The class resource, everything.
rdfs:Literal The class of literal values, e.g. textual strings and integers.
rdf:langString The class of language-tagged string literal values.
rdf:dirLangString The class of directional language-tagged string literal values.
rdf:HTML The class of HTML literal values.
rdf:XMLLiteral The class of XML literal values.
rdf:JSON The class of JSON literal values.
rdfs:Class The class of classes.
rdf:Property The class of RDF properties.
rdf:Proposition The class of reified triples.
rdfs:Datatype The class of RDF datatypes.
rdf:Statement The class of RDF statements.
rdf:Bag The class of unordered containers.
rdf:Seq The class of ordered containers.
rdf:Alt The class of containers of alternatives.
rdfs:Container The class of RDF containers.
rdfs:ContainerMembershipProperty The class of container membership properties, rdf:_1, rdf:_2, ..., all of which are sub-properties of 'member'.
rdf:List The class of RDF Lists.

RDF properties

Property name comment domain range
rdf:type The subject is an instance of a class. rdfs:Resource rdfs:Class
rdf:reifies Associates a resource with a reified triple. rdfs:Resource rdf:Proposition
rdfs:subClassOf The subject is a subclass of a class. rdfs:Class rdfs:Class
rdfs:subPropertyOf The subject is a subproperty of a property. rdf:Property rdf:Property
rdfs:domain A domain of the subject property. rdf:Property rdfs:Class
rdfs:range A range of the subject property. rdf:Property rdfs:Class
rdfs:label A human-readable name for the subject. rdfs:Resource rdfs:Literal
rdfs:comment A description of the subject resource. rdfs:Resource rdfs:Literal
rdfs:member A member of the subject resource. rdfs:Resource rdfs:Resource
rdf:first The first item in the subject RDF list. rdf:List rdfs:Resource
rdf:rest The rest of the subject RDF list after the first item. rdf:List rdf:List
rdfs:seeAlso Further information about the subject resource. rdfs:Resource rdfs:Resource
rdfs:isDefinedBy The definition of the subject resource. rdfs:Resource rdfs:Resource
rdf:value Idiomatic property used for structured values. rdfs:Resource rdfs:Resource
rdf:subject The subject of the subject RDF statement. rdf:Statement rdfs:Resource
rdf:predicate The predicate of the subject RDF statement. rdf:Statement rdfs:Resource
rdf:object The object of the subject RDF statement. rdf:Statement rdfs:Resource

In addition to these classes and properties, RDF also uses properties called rdf:_1, rdf:_2, rdf:_3... etc., each of which is both a sub-property of rdfs:member and an instance of the class rdfs:ContainerMembershipProperty. There is also an instance of rdf:List called rdf:nil that is an empty rdf:List.

Acknowledgments

Acknowledgments for 2004 Recommendation

The RDF Schema design was originally produced by the RDF Schema Working Group (1997-2000).

David Singer of IBM was the chair of the original RDF Schema group throughout most of the development of this specification; we thank David for his efforts and thank IBM for supporting him and us in this endeavor. Particular thanks are also due to Andrew Layman for his editorial work on early versions of this specification.

The original RDF Schema Working Group membership included:

Nick Arnett (Verity), Dan Brickley (ILRT / University of Bristol), Walter Chang (Adobe), Sailesh Chutani (Oracle), Ron Daniel (DATAFUSION), Charles Frankston (Microsoft), Joe Lapp (webMethods Inc.), Patrick Gannon (CommerceNet), RV Guha (Epinions, previously of Netscape Communications), Tom Hill (Apple Computer), Renato Iannella (DSTC), Sandeep Jain (Oracle), Kevin Jones, (InterMind), Emiko Kezuka (Digital Vision Laboratories), Ora Lassila (Nokia Research Center), Andrew Layman (Microsoft), John McCarthy (Lawrence Berkeley National Laboratory), Michael Mealling (Network Solutions), Norbert Mikula (DataChannel), Eric Miller (OCLC), Frank Olken (Lawrence Berkeley National Laboratory), Sri Raghavan (Digital/Compaq), Lisa Rein (webMethods Inc.), Tsuyoshi Sakata (Digital Vision Laboratories), Leon Shklar (Pencom Web Works), David Singer (IBM), Wei (William) Song (SISU), Neel Sundaresan (IBM), Ralph Swick (W3C), Naohiko Uramoto (IBM), Charles Wicksteed (Reuters Ltd.), Misha Wolf (Reuters Ltd.)

Acknowledgments for RDF 1.1

The current specification is largely an editorial clarification of that design, and has benefited greatly from the hard work of the RDF Core Working Group members, and from implementation feedback from many members of the RDF Interest Group. In 2013-2014 Guus Schreiber edited this document on behalf of the RDF Working Group to bring it in line with the RDF 1.1 specifications.

Acknowledgments for RDF 1.2

In addition to the editors, the following people have contributed to this specification:

Recognize members of the Task Force? Not an easy to find list of contributors.

Change since 2004 Recommendation

Changes for RDF 1.1 Recommendation

Changes between RDF 1.1 and RDF 1.2