Document Status Update, 1 December 2023
The Latest version link was fixed: it is intended to point to the latest version of the document for this version of RDF (i.e. RDF 1.0).
Please refer to the errata for this document, which may include some normative corrections.
See also translations.
Copyright © 2004 W3C® (MIT, ERCIM, Keio), All Rights Reserved. W3C liability, trademark, document use and software licensing rules apply.
The Resource Description Framework (RDF) is a general-purpose language for representing information in the Web.
This document defines an XML syntax for RDF called RDF/XML in terms of Namespaces in XML, the XML Information Set and XML Base. The formal grammar for the syntax is annotated with actions generating triples of the RDF graph as defined in RDF Concepts and Abstract Syntax. The triples are written using the N-Triples RDF graph serializing format which enables more precise recording of the mapping in a machine processable form. The mappings are recorded as tests cases, gathered and published in RDF Test Cases.
This document has been reviewed by W3C Members and other interested parties, and it has been endorsed by the Director as a W3C Recommendation. W3C's role in making the Recommendation is to draw attention to the specification and to promote its widespread deployment. This enhances the functionality and interoperability of the Web.
This is one document in a set of six (Primer, Concepts, Syntax, Semantics, Vocabulary, and Test Cases) intended to jointly replace the original Resource Description Framework specifications, RDF Model and Syntax (1999 Recommendation) and RDF Schema (2000 Candidate Recommendation). It has been developed by the RDF Core Working Group as part of the W3C Semantic Web Activity (Activity Statement, Group Charter) for publication on 10 February 2004.
Changes to this document since the Proposed Recommendation Working Draft are detailed in the change log.
The public is invited to send comments to [email protected] (archive) and to participate in general discussion of related technology on [email protected] (archive).
A list of implementations is available.
The W3C maintains a list of any patent disclosures related to this work.
This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.
1 Introduction
2 An XML Syntax for RDF
2.1 Introduction
2.2 Node Elements and Property Elements
2.3 Multiple Property Elements
2.4 Empty Property Elements
2.5 Property Attributes
2.6 Completing the Document: Document Element and XML Declaration
2.7 Languages: xml:lang
2.8 XML Literals: rdf:parseType="Literal"
2.9 Typed Literals: rdf:datatype
2.10 Identifying Blank Nodes: rdf:nodeID
2.11 Omitting Blank Nodes: rdf:parseType="Resource"
2.12 Omitting Nodes: Property Attributes on an empty Property Element
2.13 Typed Node Elements
2.14 Abbreviating URI References: rdf:ID
and xml:base
2.15 Container Membership Property Elements: rdf:li
and rdf:_
n
2.16 Collections: rdf:parseType="Collection"
2.17 Reifying Statements: rdf:ID
3 Terminology
4 RDF MIME Type, File Extension and Macintosh File Type
5 Global Issues
5.1 The RDF Namespace and Vocabulary
5.2 Identifiers
5.3 Resolving URIs
5.4 Constraints
5.5 Conformance
6 Syntax Data Model
6.1 Events
6.2 Information Set Mapping
6.3 Grammar Notation
7 RDF/XML Grammar
7.1 Grammar Summary
7.2 Grammar Productions
7.3 Reification Rules
7.4 List Expansion Rules
8 Serializing an RDF Graph to RDF/XML
9 Using RDF/XML with HTML and XHTML
10 Using RDF/XML with SVG
11 Acknowledgments
12 References
A Syntax Schemas (Informative)
A.1 RELAX NG Compact Syntax Schema (Informative)
B Revisions since Working Draft 10 October 2003 (Informative)
This document defines the XML [XML] syntax for RDF graphs which was originally defined in the RDF Model & Syntax [RDF-MS] W3C Recommendation. Subsequent implementations of this syntax and comparison of the resulting RDF graphs have shown that there was ambiguity — implementations generated different graphs and certain syntax forms were not widely implemented.
This document revises the original RDF/XML grammar in terms of XML Information Set [INFOSET] information items which moves away from the rather low-level details of XML, such as particular forms of empty elements. This allows the grammar to be more precisely recorded and the mapping from the XML syntax to the RDF Graph more clearly shown. The mapping to the RDF graph is done by emitting statements in the form defined in the N-Triples section of RDF Test Cases [RDF-TESTS] which creates an RDF graph, that has semantics defined by RDF Semantics [RDF-SEMANTICS].
The complete specification of RDF consists of a number of documents:
For a longer introduction to the RDF/XML syntax with a historical perspective, see RDF: Understanding the Striped RDF/XML Syntax [STRIPEDRDF].
This section introduces the RDF/XML syntax, describes how it encodes RDF graphs and explains this with examples. If there is any conflict between this informal description and the formal description of the syntax and grammar in sections 6 Syntax Data Model and 7 RDF/XML Grammar, the latter two sections take precedence.
The RDF Concepts and Abstract Syntax [RDF-CONCEPTS] defines the RDF Graph data model (Section 3.1) and the RDF Graph abstract syntax (Section 6). Along with the RDF Semantics [RDF-SEMANTICS] this provides an abstract syntax with a formal semantics for it. The RDF graph has nodes and labeled directed arcs that link pairs of nodes and this is represented as a set of RDF triples where each triple contains a subject node, predicate and object node. Nodes are RDF URI references, RDF literals or are blank nodes. Blank nodes may be given a document-local, non-RDF URI references identifier called a blank node identifier. Predicates are RDF URI references and can be interpreted as either a relationship between the two nodes or as defining an attribute value (object node) for some subject node.
In order to encode the graph in XML, the nodes and predicates have to be represented in XML terms — element names, attribute names, element contents and attribute values. RDF/XML uses XML QNames as defined in Namespaces in XML [XML-NS] to represent RDF URI references. All QNames have a namespace name which is a URI reference and a short local name. In addition, QNames can either have a short prefix or be declared with the default namespace declaration and have none (but still have a namespace name)
The RDF URI reference represented by a QName is determined by appending the local name part of the QName after the namespace name (URI reference) part of the QName. This is used to shorten the RDF URI references of all predicates and some nodes. RDF URI references identifying subject and object nodes can also be stored as XML attribute values. RDF literals, which can only be object nodes, become either XML element text content or XML attribute values.
A graph can be considered a collection of paths of the form node, predicate arc, node, predicate arc, node, predicate arc, ... node which cover the entire graph. In RDF/XML these turn into sequences of elements inside elements which alternate between elements for nodes and predicate arcs. This has been called a series of node/arc stripes. The node at the start of the sequence turns into the outermost element, the next predicate arc turns into a child element, and so on. The stripes generally start at the top of an RDF/XML document and always begin with nodes.
Several RDF/XML examples are given in the following sections building up to complete RDF/XML documents. Example 7 is the first complete RDF/XML document.
An RDF graph is given in Figure 1 where the nodes are represented as ovals and contain their RDF URI references where they have them, all the predicate arcs are labeled with RDF URI references and plain literal nodes have been written in rectangles.
If we follow one node, predicate arc ... , node path through the graph shown in Figure 2:
The left hand side of the Figure 2 graph corresponds to the node/predicate arc stripes:
http://www.w3.org/TR/rdf-syntax-grammar
http://example.org/terms/editor
http://example.org/terms/homePage
http://purl.org/net/dajobe/
In RDF/XML, the sequence of 5 nodes and predicate arcs on
the left hand side of Figure 2 corresponds to
the usage of five XML elements of two types, for the graph nodes and
predicate arcs. These are conventionally called node elements and
property elements respectively. In the striping shown in
Example 1, rdf:Description
is the
node element (used three times for the three nodes) and
ex:editor
and ex:homePage
are the two
property elements.
<rdf:Description>
<ex:editor>
<rdf:Description>
<ex:homePage>
<rdf:Description>
</rdf:Description>
</ex:homePage>
</rdf:Description>
</ex:editor>
</rdf:Description>
The Figure 2 graph consists of some nodes
that are
RDF URI references
(and others that are not) and this can be added
to the RDF/XML using the rdf:about
attribute on node
elements to give the result in Example 2:
<rdf:Description rdf:about="http://www.w3.org/TR/rdf-syntax-grammar"> <ex:editor> <rdf:Description> <ex:homePage> <rdf:Description rdf:about="http://purl.org/net/dajobe/"> </rdf:Description> </ex:homePage> </rdf:Description> </ex:editor> </rdf:Description>
Adding the other two paths through the Figure 1 graph to the RDF/XML in Example 2 gives the result in Example 3 (this example fails to show that the blank node is shared between the two paths, see 2.10):
<rdf:Description rdf:about="http://www.w3.org/TR/rdf-syntax-grammar"> <ex:editor> <rdf:Description> <ex:homePage> <rdf:Description rdf:about="http://purl.org/net/dajobe/"> </rdf:Description> </ex:homePage> </rdf:Description> </ex:editor> </rdf:Description> <rdf:Description rdf:about="http://www.w3.org/TR/rdf-syntax-grammar"> <ex:editor> <rdf:Description> <ex:fullName>Dave Beckett</ex:fullName> </rdf:Description> </ex:editor> </rdf:Description> <rdf:Description rdf:about="http://www.w3.org/TR/rdf-syntax-grammar"> <dc:title>RDF/XML Syntax Specification (Revised)</dc:title> </rdf:Description>
There are several abbreviations that can be used to make common uses easier to write down. In particular, it is common that a subject node in the RDF graph has multiple outgoing predicate arcs. RDF/XML provides an abbreviation for the corresponding syntax when a node element about a resource has multiple property elements. This can be abbreviated by using multiple child property elements inside the node element describing the subject node.
Taking Example 3, there are
two node elements that can take multiple property elements.
The subject node with URI reference
http://www.w3.org/TR/rdf-syntax-grammar
has property elements ex:editor
and ex:title
and the node element for the blank node can take ex:homePage
and ex:fullName
. This abbreviation
gives the result shown in Example 4
(this example does show that there is a single blank node):
<rdf:Description rdf:about="http://www.w3.org/TR/rdf-syntax-grammar"> <ex:editor> <rdf:Description> <ex:homePage> <rdf:Description rdf:about="http://purl.org/net/dajobe/"> </rdf:Description> </ex:homePage> <ex:fullName>Dave Beckett</ex:fullName> </rdf:Description> </ex:editor> <dc:title>RDF/XML Syntax Specification (Revised)</dc:title> </rdf:Description>
When a predicate arc in an RDF graph points to an object node which has no
further predicate arcs, which appears in RDF/XML as an empty node element
<rdf:Description rdf:about="...">
</rdf:Description>
(or <rdf:Description rdf:about="..." />
)
this form can be shortened. This is done by using the
RDF URI reference
of the object node as the value of an XML attribute rdf:resource
on the containing property element and making the property element empty.
In this example, the property element ex:homePage
contains an empty node element with the
RDF URI reference
http://purl.org/net/dajobe/
. This can be replaced with
the empty property element form giving the result shown in
Example 5:
<rdf:Description rdf:about="http://www.w3.org/TR/rdf-syntax-grammar"> <ex:editor> <rdf:Description> <ex:homePage rdf:resource="http://purl.org/net/dajobe/"/> <ex:fullName>Dave Beckett</ex:fullName> </rdf:Description> </ex:editor> <dc:title>RDF/XML Syntax Specification (Revised)</dc:title> </rdf:Description>
When a property element's content is string literal,
it may be possible to use it as an XML attribute on the
containing node element.
This can be done for multiple properties on the same node element
only if the property element name is not repeated
(required by XML — attribute names are unique on an XML element)
and any in-scope xml:lang
on the
property element's string literal (if any) are the same (see Section 2.7)
This abbreviation is known as a Property Attribute
and can be applied to any node element.
This abbreviation can also be used when the property element is
rdf:type
and it has an rdf:resource
attribute
the value of which is interpreted as a
RDF URI reference object node.
In Example 5:,
there are two property elements with string literal content,
the dc:title
and ex:fullName
property elements. These can be replaced with property attributes
giving the result shown in Example 6:
<rdf:Description rdf:about="http://www.w3.org/TR/rdf-syntax-grammar" dc:title="RDF/XML Syntax Specification (Revised)"> <ex:editor> <rdf:Description ex:fullName="Dave Beckett"> <ex:homePage rdf:resource="http://purl.org/net/dajobe/"/> </rdf:Description> </ex:editor> </rdf:Description>
To create a complete RDF/XML document, the serialization of the
graph into XML is usually contained inside an rdf:RDF
XML element which becomes the top-level XML document element.
Conventionally the rdf:RDF
element is also used to
declare the XML namespaces that are used, although that is not
required. When there is only one top-level node element inside
rdf:RDF
, the rdf:RDF
can be omitted
although any XML namespaces must still be declared.
The XML specification also permits an XML declaration at the top of the document with the XML version and possibly the XML content encoding. This is optional but recommended.
Completing the RDF/XML could be done for any of the correct complete graph examples from Example 4 onwards but taking the smallest Example 6 and adding the final components, gives a complete RDF/XML representation of the original Figure 1 graph in Example 7:
<?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:ex="http://example.org/stuff/1.0/"> <rdf:Description rdf:about="http://www.w3.org/TR/rdf-syntax-grammar" dc:title="RDF/XML Syntax Specification (Revised)"> <ex:editor> <rdf:Description ex:fullName="Dave Beckett"> <ex:homePage rdf:resource="http://purl.org/net/dajobe/" /> </rdf:Description> </ex:editor> </rdf:Description> </rdf:RDF>
It is possible to omit rdf:RDF
in
Example 7 above since there is only one
rdf:Description
inside rdf:RDF
but this
is not shown here.
xml:lang
RDF/XML permits the use of the xml:lang
attribute as defined by
2.12 Language Identification
of XML 1.0 [XML]
to allow the identification of content language.
The xml:lang
attribute can be used on any node element or property element
to indicate that the included content is in the given language.
Typed literals
which includes XML literals
are not affected by this attribute.
The most specific in-scope language present
(if any) is applied to property element string literal content or
property attribute values. The xml:lang=""
form
indicates the absence of a language identifier.
Some examples of marking content languages for RDF properties are shown in Example 8:
<?xml version="1.0" encoding="utf-8"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:dc="http://purl.org/dc/elements/1.1/"> <rdf:Description rdf:about="http://www.w3.org/TR/rdf-syntax-grammar"> <dc:title>RDF/XML Syntax Specification (Revised)</dc:title> <dc:title xml:lang="en">RDF/XML Syntax Specification (Revised)</dc:title> <dc:title xml:lang="en-US">RDF/XML Syntax Specification (Revised)</dc:title> </rdf:Description> <rdf:Description rdf:about="http://example.org/buecher/baum" xml:lang="de"> <dc:title>Der Baum</dc:title> <dc:description>Das Buch ist außergewöhnlich</dc:description> <dc:title xml:lang="en">The Tree</dc:title> </rdf:Description> </rdf:RDF>
rdf:parseType="Literal"
RDF allows
XML literals
([RDF-CONCEPTS] Section 5, XML Content within an RDF graph)
to be given as the object node of a predicate.
These are written in RDF/XML as content of a property element (not
a property attribute) and indicated using the
rdf:parseType="Literal"
attribute on the containing
property element.
An example of writing an XML literal is given in
Example 9 where
there is a single RDF triple with the subject node
RDF URI reference
http://example.org/item01
, the predicate
RDF URI reference
http://example.org/stuff/1.0/prop
(from
ex:prop
) and the object node with XML literal
content beginning a:Box
.
<?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:ex="http://example.org/stuff/1.0/"> <rdf:Description rdf:about="http://example.org/item01"> <ex:prop rdf:parseType="Literal" xmlns:a="http://example.org/a#"><a:Box required="true"> <a:widget size="10" /> <a:grommit id="23" /></a:Box> </ex:prop> </rdf:Description> </rdf:RDF>
rdf:datatype
RDF allows
typed literals
to be given as the object node of a predicate. Typed literals consist of a literal
string and a datatype
RDF URI reference. These are written in RDF/XML using
the same syntax for literal string nodes in the property element form
(not property attribute) but with an additional
rdf:datatype="
datatypeURI"
attribute on the property element. Any
RDF URI reference can be used in the attribute.
An example of an RDF
typed literal
is given in Example 10 where
there is a single RDF triple with the subject node
RDF URI reference
http://example.org/item01
, the predicate
RDF URI reference
http://example.org/stuff/1.0/size
(from
ex:size
) and the object node with the
typed literal
("123", http://www.w3.org/2001/XMLSchema#int
)
to be interpreted as an
W3C XML Schema
[XML-SCHEMA2] datatype int.
<?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:ex="http://example.org/stuff/1.0/"> <rdf:Description rdf:about="http://example.org/item01"> <ex:size rdf:datatype="http://www.w3.org/2001/XMLSchema#int">123</ex:size> </rdf:Description> </rdf:RDF>
rdf:nodeID
Blank nodes in the RDF graph are distinct but have no
RDF URI reference identifier.
It is sometimes required that the same graph blank node is referred to in the
RDF/XML in multiple places, such as at the subject and object
of several RDF triples. In this case, a blank node identifier
can be given to the blank node for identifying it
in the document. Blank node identifiers in RDF/XML are scoped to the
containing XML Information Set
document information item.
A blank node identifier is used
on a node element to replace
rdf:about="
RDF URI reference"
or on a property element to replace
rdf:resource="
RDF URI reference"
with rdf:nodeID="
blank node identifier"
in both cases.
Taking Example 7 and explicitly giving
a blank node identifier of abc
to the blank node in it
gives the result shown in Example 11.
The second rdf:Description
property element is
about the blank node.
rdf:nodeID
identifying the blank node (example11.rdf output example11.nt)<?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:ex="http://example.org/stuff/1.0/"> <rdf:Description rdf:about="http://www.w3.org/TR/rdf-syntax-grammar" dc:title="RDF/XML Syntax Specification (Revised)"> <ex:editor rdf:nodeID="abc"/> </rdf:Description> <rdf:Description rdf:nodeID="abc" ex:fullName="Dave Beckett"> <ex:homePage rdf:resource="http://purl.org/net/dajobe/"/> </rdf:Description> </rdf:RDF>
rdf:parseType="Resource"
Blank nodes (not RDF URI reference nodes) in RDF graphs can be written
in a form that allows the
<rdf:Description>
</rdf:Description>
pair to be omitted.
The omission is done by putting an
rdf:parseType="Resource"
attribute on the containing property element
that turns the property element into a property-and-node element,
which can itself have both property elements and property attributes.
Property attributes and the rdf:nodeID
attribute
are not permitted on property-and-node elements.
Taking the earlier Example 7,
the contents of the ex:editor
property element
could be alternatively done in this fashion to give
the form shown in Example 12:
<?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:ex="http://example.org/stuff/1.0/"> <rdf:Description rdf:about="http://www.w3.org/TR/rdf-syntax-grammar" dc:title="RDF/XML Syntax Specification (Revised)"> <ex:editor rdf:parseType="Resource"> <ex:fullName>Dave Beckett</ex:fullName> <ex:homePage rdf:resource="http://purl.org/net/dajobe/"/> </ex:editor> </rdf:Description> </rdf:RDF>
If all of the property elements on a blank node element have
string literal values with the same in-scope xml:lang
value (if present) and each of these property elements appears at
most once and there is at most one rdf:type
property
element with a RDF URI reference object node, these can be abbreviated by
moving them to be property attributes on the containing property
element which is made an empty element.
Taking the earlier Example 5,
the ex:editor
property element contains a
blank node element with two property elements
ex:fullname
and ex:homePage
.
ex:homePage
is not suitable here since it
does not have a string literal value, so it is being
ignored for the purposes of this example.
The abbreviated form removes the ex:fullName
property element
and adds a new property attribute ex:fullName
with the
string literal value of the deleted property element
to the ex:editor
property element.
The blank node element becomes implicit in the now empty
ex:editor
property element. The result is shown in
Example 13.
<?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:ex="http://example.org/stuff/1.0/"> <rdf:Description rdf:about="http://www.w3.org/TR/rdf-syntax-grammar" dc:title="RDF/XML Syntax Specification (Revised)"> <ex:editor ex:fullName="Dave Beckett" /> <!-- Note the ex:homePage property has been ignored for this example --> </rdf:Description> </rdf:RDF>
It is common for RDF graphs to have rdf:type
predicates
from subject nodes. These are conventionally called typed
nodes in the graph, or typed node elements in the
RDF/XML. RDF/XML allows this triple to be expressed more concisely.
by replacing the rdf:Description
node element name with
the namespaced-element corresponding to the
RDF URI reference of the value of
the type relationship. There may, of course, be multiple rdf:type
predicates but only one can be used in this way, the others must remain as
property elements or property attributes.
The typed node elements are commonly used in RDF/XML with the built-in
classes in the RDF vocabulary:
rdf:Seq
, rdf:Bag
, rdf:Alt
,
rdf:Statement
, rdf:Property
and
rdf:List
.
For example, the RDF/XML in Example 14 could be written as shown in Example 15.
<?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:ex="http://example.org/stuff/1.0/"> <rdf:Description rdf:about="http://example.org/thing"> <rdf:type rdf:resource="http://example.org/stuff/1.0/Document"/> <dc:title>A marvelous thing</dc:title> </rdf:Description> </rdf:RDF>
rdf:type
(example15.rdf output example15.nt)<?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:ex="http://example.org/stuff/1.0/"> <ex:Document rdf:about="http://example.org/thing"> <dc:title>A marvelous thing</dc:title> </ex:Document> </rdf:RDF>
rdf:ID
and xml:base
RDF/XML allows further abbreviating RDF URI references in XML attributes in two
ways. The XML Infoset provides a base URI attribute xml:base
that sets the base URI for resolving relative RDF URI references, otherwise the base URI is that of the document. The base URI applies to
all RDF/XML attributes that deal with RDF URI references which are rdf:about
,
rdf:resource
, rdf:ID
and rdf:datatype
.
The rdf:ID
attribute on a node element (not property
element, that has another meaning) can be used instead of
rdf:about
and gives a relative RDF URI reference equivalent to #
concatenated with the rdf:ID
attribute value. So for
example if rdf:ID="name"
, that would be equivalent
to rdf:about="#name"
. rdf:ID
provides an additional
check since the same name can only appear once in the
scope of an xml:base
value (or document, if none is given),
so is useful for defining a set of distinct,
related terms relative to the same RDF URI reference.
Both forms require a base URI to be known, either from an in-scope
xml:base
or from the URI of the RDF/XML document.
Example 16 shows abbreviating the node
RDF URI reference of http://example.org/here/#snack
using an
xml:base
of http://example.org/here/
and
an rdf:ID
on the rdf:Description
node element.
The object node of the ex:prop
predicate is an
absolute RDF URI reference
resolved from the rdf:resource
XML attribute value
using the in-scope base URI to give the
RDF URI reference
http://example.org/here/fruit/apple
.
rdf:ID
and xml:base
for shortening URIs (example16.rdf output example16.nt)<?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:ex="http://example.org/stuff/1.0/" xml:base="http://example.org/here/"> <rdf:Description rdf:ID="snack"> <ex:prop rdf:resource="fruit/apple"/> </rdf:Description> </rdf:RDF>
rdf:li
and rdf:_
nRDF has a set of container membership properties
and corresponding property elements that are mostly used with
instances of the
rdf:Seq
, rdf:Bag
and rdf:Alt
classes which may be written as typed node elements. The list properties are
rdf:_1
, rdf:_2
etc. and can be written
as property elements or property attributes as shown in
Example 17. There is an rdf:li
special property element that is equivalent to
rdf:_1
, rdf:_2
in order,
explained in detail in section 7.4.
The mapping to the container membership properties is
always done in the order that the rdf:li
special
property elements appear in XML — the document order is significant.
The equivalent RDF/XML to Example 17 written
in this form is shown in Example 18.
<?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"> <rdf:Seq rdf:about="http://example.org/favourite-fruit"> <rdf:_1 rdf:resource="http://example.org/banana"/> <rdf:_2 rdf:resource="http://example.org/apple"/> <rdf:_3 rdf:resource="http://example.org/pear"/> </rdf:Seq> </rdf:RDF>
rdf:li
property element for list properties (example18.rdf output example18.nt)<?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"> <rdf:Seq rdf:about="http://example.org/favourite-fruit"> <rdf:li rdf:resource="http://example.org/banana"/> <rdf:li rdf:resource="http://example.org/apple"/> <rdf:li rdf:resource="http://example.org/pear"/> </rdf:Seq> </rdf:RDF>
rdf:parseType="Collection"
RDF/XML allows an rdf:parseType="Collection"
attribute on a property element to let it contain multiple node
elements. These contained node elements give the set of subject
nodes of the collection. This syntax form corresponds to a set of
triples connecting the collection of subject nodes, the exact triples
generated are described in detail in
Section 7.2.19 Production parseTypeCollectionPropertyElt.
The collection construction is always done in the order that the node
elements appear in the XML document. Whether the order of the
collection of nodes is significant is an application issue and not
defined here.
Example 19 shows a collection of three
nodes elements at the end of the ex:hasFruit
property element using this form.
rdf:parseType="Collection"
(example19.rdf output example19.nt)<?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:ex="http://example.org/stuff/1.0/"> <rdf:Description rdf:about="http://example.org/basket"> <ex:hasFruit rdf:parseType="Collection"> <rdf:Description rdf:about="http://example.org/banana"/> <rdf:Description rdf:about="http://example.org/apple"/> <rdf:Description rdf:about="http://example.org/pear"/> </ex:hasFruit> </rdf:Description> </rdf:RDF>
rdf:ID
The rdf:ID
attribute can be used on a property
element to reify the triple that it generates (See
section 7.3 Reification Rules for the
full details).
The identifier for the triple should be constructed as a
RDF URI reference
made from the relative URI reference
#
concatenated with the rdf:ID
attribute
value, resolved against the in-scope base URI. So for example if
rdf:ID="triple"
, that would be equivalent to the RDF URI reference
formed from relative URI reference #triple
against the base URI.
Each (rdf:ID
attribute value, base URI)
pair has to be unique in an RDF/XML document,
see constraint-id.
Example 20 shows a rdf:ID
being used to reify a triple made from the ex:prop
property element giving the reified triple the
RDF URI reference http://example.org/triples/#triple1
.
rdf:ID
reifying a property element (example20.rdf output example20.nt)<?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:ex="http://example.org/stuff/1.0/" xml:base="http://example.org/triples/"> <rdf:Description rdf:about="http://example.org/"> <ex:prop rdf:ID="triple1">blah</ex:prop> </rdf:Description> </rdf:RDF>
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [KEYWORDS].
All use of string without further qualification refers to a Unicode[UNICODE] character string; a sequence of characters represented by a code point in Unicode. (Such as defined in [CHARMOD] in section 3.4 Strings).
The Internet media type / MIME type for RDF/XML is
"application/rdf+xml
" —
see RFC 3023
[RFC-3023] section 8.18.
Registration Note (Informative): For the state of the MIME type registration, consult IANA MIME Media Types [IANA-MEDIA-TYPES]
It is recommended that RDF/XML files have the extension
".rdf"
(all lowercase) on all platforms.
It is recommended that RDF/XML files stored on Macintosh HFS file
systems be given a file type of "rdf "
(all lowercase, with a space character as the fourth letter).
Note (Informative):
The names aboutEach
and aboutEachPrefix
were removed
from the language and the RDF vocabulary by the RDF Core Working Group.
See the resolution of issues
rdfms-abouteach and
rdfms-abouteachprefix
for further information.
Note (Informative):
The names List
, first
,
rest
and nil
were added for issue
rdfms-seq-representation.
The names XMLLiteral
and datatype
were added
to support RDF datatyping.
The name nodeID
was added
for issue
rdfms-syntax-incomplete.
See the
RDF Core Issues List
for further information.
The
RDF namespace URI reference (or namespace name) is
http://www.w3.org/1999/02/22-rdf-syntax-ns#
and is typically used in XML with the prefix rdf
although other prefix strings may be used.
The RDF Vocabulary
is identified by this namespace name and consists of the following names only:
RDF Description ID about parseType resource li nodeID datatype
Seq Bag Alt Statement Property XMLLiteral List
subject predicate object type value first rest _
n
where n is a decimal integer greater than zero with no leading zeros.
nil
Any other names are not defined and SHOULD generate a warning when encountered, but should otherwise behave normally.
Within RDF/XML documents it is not permitted to use XML namespaces whose namespace name is the ·RDF namespace URI reference· concatenated with additional characters.
Throughout this document the terminology rdf:
name
will be used to indicate name is from the RDF vocabulary
and it has a RDF URI reference of the concatenation of the
·RDF namespace URI reference· and name.
For example, rdf:type
has the RDF URI reference
http://www.w3.org/1999/02/22-rdf-syntax-ns#type
The RDF Graph (RDF Concepts and Abstract Syntax Section 3) defines three types of nodes and one type of predicate:
RDF URI references (RDF Concepts and Abstract Syntax Section 3.1) can be either:
rdf:ID
attribute values.Within RDF/XML, XML QNames are transformed into
RDF URI references
by appending the XML local name to the namespace name (URI reference).
For example, if the XML namespace prefix foo
has
namespace name (URI reference)
http://example.org/somewhere/
then the QName
foo:bar
would correspond to the RDF URI reference
http://example.org/somewhere/bar
. Note that this
restricts which
RDF URI references can be made and the same URI can be given in multiple ways.
The rdf:ID
values
are transformed into
RDF URI references
by appending the attribute value to the result of appending
"#" to the in-scope base URI which is defined in
Section 5.3 Resolving URIs
RDF literals (RDF Concepts and Abstract Syntax 6.5) are either plain literals (ibid), or typed literals (ibid). The latter includes XML literals (ibid section 5, XML Content within an RDF graph).
Blank nodes have distinct identity in the RDF graph.
When the graph is written in a syntax such as RDF/XML, these
blank nodes may need graph-local identifiers and a syntax
in order to preserve this distinction. These local identifiers are called
blank node identifiers
and are used in RDF/XML as values of the rdf:nodeID
attribute
with the syntax given in Production nodeIdAttr.
Blank node identifiers in RDF/XML are scoped to the XML Information Set
document information item.
If no blank node identifier is given explicitly as an
rdf:nodeID
attribute value then one will need to be
generated (using generated-blank-node-id, see section 6.3.3).
Such generated blank node
identifiers must not clash with any blank node identifiers derived
from rdf:nodeID
attribute values. This can be
implemented by any method that preserves the distinct identity of all
the blank nodes in the graph, that is, the same blank node identifier
is not given for different blank nodes. One possible method would be
to add a constant prefix to all the rdf:nodeID
attribute
values and ensure no generated blank node identifiers ever used that
prefix. Another would be to map all rdf:nodeID
attribute
values to new generated blank node identifiers and perform that mapping
on all such values in the RDF/XML document.
RDF/XML supports
XML Base [XML-BASE]
which defines a
·base-uri·
accessor for each
·root event· and
·element event·.
Relative URI references are resolved into
RDF URI references
according to the algorithm specified in
XML Base [XML-BASE]
(and RFC 2396).
These specifications do not specify an algorithm for resolving a
fragment identifier alone, such as #foo
, or the empty
string ""
into an
RDF URI reference. In RDF/XML, a fragment identifier
is transformed into a
RDF URI reference
by appending the fragment identifier to the in-scope base URI. The
empty string is transformed
into an
RDF URI reference
by substituting the in-scope base URI.
Test: Indicated by test001.rdf and test001.nt
Test: Indicated by test004.rdf and test004.nt
Test: Indicated by test008.rdf and test008.nt
Test: Indicated by test013.rdf and test013.nt
Test: Indicated by test016.rdf and test016.nt
An empty same document reference "" resolves against the URI part of the base URI; any fragment part is ignored. See Uniform Resource Identifiers (URI) [URIS] section 4.2
Test: Indicated by test013.rdf and test013.nt
Implementation Note (Informative): When using a hierarchical base URI that has no path component (/), it must be added before using as a base URI for resolving.
Test: Indicated by test011.rdf and test011.nt
Each application of production idAttr matches an attribute. The pair formed by the ·string-value· accessor of the matched attribute and the ·base-uri· accessor of the matched attribute is unique within a single RDF/XML document.
The syntax of the names must match the rdf-id production.
Test: Indicated by test014.rdf and test014.nt
This document specifies the syntax of RDF/XML as a grammar on an alphabet of symbols. The symbols are called events in the style of the [XPATH] Information Set Mapping. A sequence of events is normally derived from an XML document, in which case they are in document order as defined below in Section 6.2 Information Set Mapping. The sequence these events form are intended to be similar to the sequence of events produced by the [SAX2] XML API from the same XML document. Sequences of events may be checked against the grammar to determine whether they are or are not syntactically well-formed RDF/XML.
The grammar productions may include actions which fire when the production is recognized. Taken together these actions define a transformation from any syntactically well-formed RDF/XML sequence of events into an RDF graph represented in the N-Triples language.
The model given here illustrates one way to create a representation of an RDF Graph from an RDF/XML document. It does not mandate any implementation method — any other method that results in a representation of the same RDF Graph may be used.
In particular:
The syntax does not support non-well-formed XML documents, nor documents that otherwise do not have an XML Information Set; for example, that do not conform to Namespaces in XML [XML-NS].
The Infoset requires support for XML Base [XML-BASE]. RDF/XML uses the information item property [base URI], discussed in section 5.3
This specification requires an XML Information Set [INFOSET] which supports at least the following information items and properties for RDF/XML:
There is no mapping of the following items to data model events:
Other information items and properties have no mapping to syntax data model events.
Element information items with reserved XML Names
(See Name
in XML 1.0)
are not mapped to data model element events. These are all those
with property [prefix] beginning with xml
(case
independent comparison) and all those with [prefix] property
having no value and which have [local name] beginning with
xml
(case independent comparison).
All information items contained inside XML elements matching the parseTypeLiteralPropertyElt production form XML literals and do not follow this mapping. See parseTypeLiteralPropertyElt for further information.
This section is intended to satisfy the requirements for Conformance in the [INFOSET] specification. It specifies the information items and properties that are needed to implement this specification.
There are nine types of event defined in the following subsections. Most events are constructed from an Infoset information item (except for URI reference, blank node, plain literal and typed literal). The effect of an event constructor is to create a new event with a unique identity, distinct from all other events. Events have accessor operations on them and most have the string-value accessor that may be a static value or computed.
Constructed from a document information item and takes the following accessors and values.
Constructed from an element information item and takes the following accessors and values:
Made from the value of element information item property [attributes] which is a set of attribute information items.
If this set contains an attribute information item xml:lang
(
[namespace name] property with the value
"http://www.w3.org/XML/1998/namespace" and
[local name] property value "lang")
it is removed from the set of attribute information items and the
·language· accessor is set to the
[normalized-value] property of the attribute information item.
All remaining reserved XML Names
(See Name
in XML 1.0)
are now removed from the set. These are, all
attribute information items in the set with property [prefix]
beginning with xml
(case independent
comparison) and all attribute information items with [prefix]
property having no value and which have [local name] beginning with
xml
(case independent comparison) are removed.
Note that the [base URI] accessor is computed by XML Base before any
xml:base
attribute information item is deleted.
The remaining set of attribute information items are then used to construct a new set of Attribute Events which is assigned as the value of this accessor.
The value is the concatenation of the following in this order "<", the escaped value of the ·URI· accessor and ">".
The escaping of the ·URI· accessor uses the N-Triples escapes for URI references as described in 3.3 URI References.
Has no accessors. Marks the end of the containing element in the sequence.
Constructed from an attribute information item and takes the following accessors and values:
If ·namespace-name· is present,
set to a string value of the concatenation of the value of the
·namespace-name· accessor
and the value of the
·local-name· accessor.
Otherwise if ·local-name· is
ID
, about
, resource
, parseType
or type
, set to a string value of the
concatenation of the
·RDF namespace URI reference·
and the value of the ·local-name· accessor. Other non-namespaced ·local-name· accessor values are forbidden.
The support for a limited set of non-namespaced names is REQUIRED and intended to allow RDF/XML documents specified in [RDF-MS] to remain valid; new documents SHOULD NOT use these unqualified attributes and applications MAY choose to warn when the unqualified form is seen in a document.
The construction of
RDF URI references
from XML attributes can generate the same
RDF URI references
from different XML attributes. This can cause ambiguity in the
grammar when matching attribute events (such as when
rdf:about
and about
XML attributes are
both present). Documents that have this are illegal.
The value is the concatenation of the following in this order "<", the escaped value of the ·URI· accessor and ">".
The escaping of the ·URI· accessor uses the N-Triples escapes for URI references as described in 3.3 URI References.
Constructed from a sequence of one or more consecutive character information items. Has the single accessor:
An event for a RDF URI references which has the following accessors:
The value is the concatenation of "<", the escaped value of the ·identifier· accessor and ">"
The escaping of the ·identifier· accessor value uses the N-Triples escapes for URI references as described in 3.3 URI References.
These events are constructed by giving a value for the ·identifier· accessor.
For further information on identifiers in the RDF graph, see section 5.2.
An event for a blank node identifier which has the following accessors:
These events are constructed by giving a value for the ·identifier· accessor.
For further information on identifiers in the RDF graph, see section 5.2.
An event for a plain literal which can have the following accessors:
The value is calculated from the other accessors as follows.
If ·literal-language· is the empty string then the value is the concatenation of """ (1 double quote), the escaped value of the ·literal-value· accessor and """ (1 double quote).
Otherwise the value is the concatenation of """ (1 double quote), the escaped value of the ·literal-value· accessor ""@" (1 double quote and a '@'), and the value of the ·literal-language· accessor.
The escaping of the ·literal-value· accessor value uses the N-Triples escapes for strings as described in 3.2 Strings for escaping certain characters such as ".
These events are constructed by giving values for the ·literal-value· and ·literal-language· accessors.
Interoperability Note (Informative): Literals beginning with a Unicode combining character are allowed however they may cause interoperability problems. See [CHARMOD] for further information.
An event for a typed literal which can have the following accessors:
The value is the concatenation of the following in this order """ (1 double quote), the escaped value of the ·literal-value· accessor, """ (1 double quote), "^^<", the escaped value of the ·literal-datatype· accessor and ">".
The escaping of the ·literal-value· accessor value uses the N-Triples escapes for strings as described in 3.2 Strings for escaping certain characters such as ". The escaping of the ·literal-datatype· accessor value must use the N-Triples escapes for URI references as described in 3.3 URI References.
These events are constructed by giving values for the ·literal-value· and ·literal-datatype· accessors.
Interoperability Note (Informative): Literals beginning with a Unicode combining character are allowed however they may cause interoperability problems. See [CHARMOD] for further information.
Implementation Note (Informative): In XML Schema (part 1) [XML-SCHEMA1], white space normalization occurs during validation according to the value of the whiteSpace facet. The syntax mapping used in this document occurs after this, so the whiteSpace facet formally has no further effect.
To transform the Infoset into the sequence of events in document order, each information item is transformed as described above to generate a tree of events with accessors and values. Each element event is then replaced as described below to turn the tree of events into a sequence in document order.
The following notation is used to describe matching the sequence of data model events as given in Section 6 and the actions to perform for the matches. The RDF/XML grammar is defined in terms of mapping from these matched data model events to triples, using notation of the form:
number event-type event-content
action...
where the event-content is an expression matching event-types (as defined in Section 6.1), using notation given in the following sections. The number is used for reference purposes. The grammar action may include generating new triples to the graph, written in N-Triples format.
The following sections describe the general notation used and that for event matching and actions.
Notation | Meaning |
---|---|
event.accessor | The value of an event accessor. |
rdf: X |
A URI as defined in section 5.1. |
"ABC" | A string of characters A, B, C in order. |
Notation | Meaning |
---|---|
A == B | Event accessor A matches expression B. |
A != B | A is not equal to B. |
A | B | ... | The A, B, ... terms are alternatives. |
A - B | The terms in A excluding all the terms in B. |
anyURI. | Any URI. |
anyString. | Any string. |
list(item1, item2, ...); list() | An ordered list of events. An empty list. |
set(item1, item2, ...); set() | An unordered set of events. An empty set. |
* | Zero or more of preceding term. |
? | Zero or one of preceding term. |
+ | One or more of preceding term. |
root(acc1 == value1, acc2 == value2, ...) |
Match a Root Event with accessors. |
start-element(acc1 == value1, acc2 == value2, ...) children end-element() |
Match a sequence of Element Event with accessors, a possibly empty list of events as element content and an End Element Event. |
attribute(acc1 == value1, acc2 == value2, ...) |
Match an Attribute Event with accessors. |
text() | Match a Text Event. |
Notation | Meaning |
---|---|
A := B | Assigns A the value B. |
concat(A, B, ..) | A string created by concatenating the terms in order. |
resolve(e, s) | A string created by interpreting string s as a relative URI reference to the ·base-uri· accessor of e as defined in Section 5.3 Resolving URIs. The resulting string represents an RDF URI reference. |
generated-blank-node-id() | A string value for a new distinct generated blank node identifier as defined in section 5.2 Identifiers. |
event.accessor := value | Sets an event accessor to the given value. |
uri(identifier := value) | Create a new URI Reference Event. |
bnodeid(identifier := value) | Create a new Blank Node Identifier Event. See also section 5.2 Identifiers. |
literal(literal-value := string, literal-language := language, ...) |
Create a new Plain Literal Event. |
typed-literal(literal-value := string, ...) | Create a new Typed Literal Event. |
If the RDF/XML is a standalone XML document (identified by presentation as an application/rdf+xml RDF MIME type object, or by some other means) then the grammar may start with production doc or production nodeElement.
If the content is known to be RDF/XML by context, such as when RDF/XML is embedded inside other XML content, then the grammar can either start at Element Event RDF (only when an element is legal at that point in the XML) or at production nodeElementList (only when element content is legal, since this is a list of elements). For such embedded RDF/XML, the ·base-uri· value on the outermost element must be initialized from the containing XML since no Root Event will be available. Note that if such embedding occurs, the grammar may be entered several times but no state is expected to be preserved.
rdf:RDF
| rdf:ID
| rdf:about
| rdf:parseType
| rdf:resource
| rdf:nodeID
| rdf:datatype
A subset of the syntax terms from the RDF vocabulary in section 5.1 which are used in RDF/XML.
coreSyntaxTerms | rdf:Description
| rdf:li
All the syntax terms from the RDF vocabulary in section 5.1 which are used in RDF/XML.
rdf:aboutEach
| rdf:aboutEachPrefix
| rdf:bagID
These are the names from the RDF vocabulary that have been withdrawn from the language. See the resolutions of Issue rdfms-aboutEach-on-object, Issue rdfms-abouteachprefix and Last Call Issue timbl-01 for further information.
Error Test: Indicated by error001.rdf and error002.rdf
anyURI - ( coreSyntaxTerms | rdf:li
| oldTerms )
The RDF URI references that are allowed on node elements.
anyURI - ( coreSyntaxTerms | rdf:Description
| oldTerms )
The URIs that are allowed on property elements.
anyURI - ( coreSyntaxTerms | rdf:Description
| rdf:li
| oldTerms )
The RDF URI references that are allowed on property attributes.
root(document-element == RDF,
children == list(RDF))
start-element(URI == rdf:RDF
,
attributes == set())
nodeElementList
end-element()
ws* (nodeElement ws* )*
start-element(URI == nodeElementURIs
attributes == set((idAttr | nodeIdAttr | aboutAttr )?, propertyAttr*))
propertyEltList
end-element()
For node element e, the processing of some of the attributes has to be done before other work such as dealing with children events or other attributes. These can be processed in any order:
rdf:ID
, then
e.subject := uri(identifier := resolve(e, concat("#", a.string-value))).rdf:nodeID
, then
e.subject := bnodeid(identifier:=a.string-value).rdf:about
then
e.subject := uri(identifier := resolve(e, a.string-value)).If e.subject is empty, then e.subject := bnodeid(identifier := generated-blank-node-id()).
The following can then be performed in any order:
rdf:Description
then the following statement is added to the graph:
e.subject.string-value <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> e.URI-string-value .
rdf:type
then
u:=uri(identifier:=resolve(a.string-value))
and the following tiple is added to the graph:
e.subject.string-value <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> u.string-value .
rdf:type
),
the Unicode string
a.string-value
SHOULD be in Normal Form C[NFC],
o := literal(literal-value := a.string-value, literal-language := e.language)
and the following statement is added to the graph:
A text event matching white space defined by [XML] definition White Space Rule [3] S in section Common Syntactic Constructs
ws* (propertyElt ws* ) *
If element e has
e.URI =
rdf:li
then apply the list expansion rules on element e.parent in
section 7.4
to give a new URI u and
e.URI := u.
The action of this production must be done before the actions of any sub-matches (resourcePropertyElt ... emptyPropertyElt). Alternatively the result must be equivalent to as if it this action was performed first, such as performing as the first action of all of the sub-matches.
start-element(URI == propertyElementURIs ),
attributes == set(idAttr?))
ws* nodeElement ws*
end-element()
For element e, and the single contained nodeElement n, first n must be processed using production nodeElement. Then the following statement is added to the graph:
e.parent.subject.string-value e.URI-string-value n.subject.string-value .
If the rdf:ID
attribute a is given, the above
statement is reified with
i := uri(identifier := resolve(e, concat("#", a.string-value)))
using the reification rules in
section 7.3
and e.subject := i
start-element(URI == propertyElementURIs ),
attributes == set(idAttr?, datatypeAttr?))
text()
end-element()
Note that the empty literal case is defined in production emptyPropertyElt.
For element e, and the text event t.
The Unicode string t.string-value SHOULD be in Normal Form C[NFC].
If the rdf:datatype
attribute d is given
then o := typed-literal(literal-value := t.string-value, literal-datatype := d.string-value)
otherwise
o := literal(literal-value := t.string-value, literal-language := e.language)
and the following statement is added to the graph:
e.parent.subject.string-value e.URI-string-value o.string-value .
If the rdf:ID
attribute a is given, the above
statement is reified with
i := uri(identifier := resolve(e, concat("#", a.string-value)))
using the reification rules in
section 7.3
and e.subject := i.
start-element(URI == propertyElementURIs ),
attributes == set(idAttr?, parseLiteral))
literal
end-element()
For element e and the literal l
that is the rdf:parseType="Literal"
content.
l is not transformed by the syntax data model mapping into events
(as noted in 6 Syntax Data Model)
but remains an XML Infoset of XML Information items.
l is transformed into the lexical form of an XML literal in the RDF graph x (a Unicode string) by the following algorithm. This does not mandate any implementation method — any other method that gives the same result may be used.
Then o := typed-literal(literal-value := x, literal-datatype := http://www.w3.org/1999/02/22-rdf-syntax-ns#XMLLiteral
)
and the following statement is added to the graph:
e.parent.subject.string-value e.URI-string-value o.string-value .
Test: Empty literal case indicated by test009.rdf and test009.nt
If the rdf:ID
attribute a is given, the above
statement is reified with
i := uri(identifier := resolve(e, concat("#", a.string-value)))
using the reification rules in
section 7.3
and e.subject := i.
start-element(URI == propertyElementURIs ),
attributes == set(idAttr?, parseResource))
propertyEltList
end-element()
For element e with possibly empty element content c.
n := bnodeid(identifier := generated-blank-node-id()).
Add the following statement to the graph:
e.parent.subject.string-value e.URI-string-value n.string-value .
Test: Indicated by test004.rdf and test004.nt
If the rdf:ID
attribute a is given, the
statement above is reified with
i := uri(identifier := resolve(e, concat("#", a.string-value)))
using the reification rules in
section 7.3
and e.subject := i.
If the element content c is not empty, then use event n to create a new sequence of events as follows:
start-element(URI := rdf:Description
,
subject := n,
attributes := set())
c
end-element()
Then process the resulting sequence using production nodeElement.
start-element(URI == propertyElementURIs ),
attributes == set(idAttr?, parseCollection))
nodeElementList
end-element()
For element event e with possibly empty nodeElementList l. Set s:=list().
For each element event f in l, n := bnodeid(identifier := generated-blank-node-id()) and append n to s to give a sequence of events.
If s is not empty, n is the first event identifier in s and the following statement is added to the graph:
e.parent.subject.string-value e.URI-string-value n.string-value .
otherwise the following statement is added to the graph:
e.parent.subject.string-value e.URI-string-value <http://www.w3.org/1999/02/22-rdf-syntax-ns#nil> .
If the rdf:ID
attribute a is given,
either of the the above statements is reified with
i := uri(identifier := resolve(e, concat("#", a.string-value)))
using the reification rules in
section 7.3.
If s is empty, no further work is performed.
For each event n in s and the corresponding element event f in l, the following statement is added to the graph:
n.string-value <http://www.w3.org/1999/02/22-rdf-syntax-ns#first> f.string-value .
For each consecutive and overlapping pair of events (n, o) in s, the following statement is added to the graph:
n.string-value <http://www.w3.org/1999/02/22-rdf-syntax-ns#rest> o.string-value .
If s is not empty, n is the last event identifier in s, the following statement is added to the graph:
n.string-value <http://www.w3.org/1999/02/22-rdf-syntax-ns#rest> <http://www.w3.org/1999/02/22-rdf-syntax-ns#nil> .
start-element(URI == propertyElementURIs ),
attributes == set(idAttr?, parseOther))
propertyEltList
end-element()
All rdf:parseType
attribute values other than the strings
"Resource", "Literal" or "Collection" are treated as if the value was
"Literal". This production matches and acts as if production
parseTypeLiteralPropertyElt
was matched.
No extra triples are generated for other rdf:parseType
values.
start-element(URI == propertyElementURIs ),
attributes == set(idAttr?, ( resourceAttr | nodeIdAttr )?, propertyAttr*))
end-element()
If there are no attributes or only the
optional rdf:ID
attribute i
then o := literal(literal-value:="", literal-language := e.language)
and the following statement is added to the graph:
e.parent.subject.string-value e.URI-string-value o.string-value .
and then if i is given, the above statement is reified with uri(identifier := resolve(e, concat("#", i.string-value))) using the reification rules in section 7.3.
Test: Indicated by test002.rdf and test002.nt
Test: Indicated by test005.rdf and test005.nt
Otherwise
rdf:resource
attribute i is present, then
r := uri(identifier := resolve(e, i.string-value))
rdf:nodeID
attribute i is present, then
r := bnodeid(identifier := i.string-value)
The following are done in any order:
For all propertyAttr attributes a (in any order)
If a.URI == rdf:type
then u:=uri(identifier:=resolve(a.string-value))
and the following triple is added to the graph:
r.string-value <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> u.string-value .
Otherwise Unicode string a.string-value SHOULD be in Normal Form C[NFC], o := literal(literal-value := a.string-value, literal-language := e.language) and the following statement is added to the graph:
r.string-value a.URI-string-value o.string-value .
Test: Indicated by test013.rdf and test013.nt
Test: Indicated by test014.rdf and test014.nt
Add the following statement to the graph:
e.parent.subject.string-value e.URI-string-value r.string-value .
and then if rdf:ID
attribute i is given, the above statement is
reified with
uri(identifier := resolve(e, concat("#", i.string-value)))
using the reification rules in
section 7.3.
attribute(URI == rdf:ID
,
string-value == rdf-id)
Constraint:: constraint-id
applies to the values of rdf:ID
attributes
attribute(URI == rdf:nodeID
,
string-value == rdf-id)
attribute(URI == rdf:about
,
string-value == URI-reference)
attribute(URI == propertyAttributeURIs,
string-value == anyString)
attribute(URI == rdf:resource
,
string-value == URI-reference)
attribute(URI == rdf:datatype
,
string-value == URI-reference)
attribute(URI == rdf:parseType
,
string-value == "Literal")
attribute(URI == rdf:parseType
,
string-value == "Resource")
attribute(URI == rdf:parseType
,
string-value == "Collection")
attribute(URI == rdf:parseType
,
string-value == anyString - ("Resource" | "Literal" | "Collection") )
Any XML element content that is allowed according to [XML] definition Content of Elements Rule [43] content. in section 3.1 Start-Tags, End-Tags, and Empty-Element Tags
The string-value for the resulting event is discussed in section 7.2.17.
An attribute ·string-value· matching any legal [XML-NS] token NCName
For the given URI reference event r and the statement with terms s, p and o corresponding to the N-Triples:
s p o .
add the following statements to the graph:
r.string-value <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> s .
r.string-value <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> p .
r.string-value <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> o .
r.string-value <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/1999/02/22-rdf-syntax-ns#Statement> .
For the given element e, create a new RDF URI reference u := concat("http://www.w3.org/1999/02/22-rdf-syntax-ns#_", e.li-counter), increment the e.li-counter property by 1 and return u.
There are some RDF Graphs as defined in RDF Concepts and Abstract Syntax that cannot be serialized in RDF/XML. These are those that:
Implementation Note (Informative): When an RDF graph is serialized to RDF/XML and has an XML Schema Datatype (XSD), it SHOULD be written in a form that does not require whitespace processing. XSD support is NOT required by RDF or RDF/XML so this is optional.
If RDF/XML is embedded inside HTML or XHTML this can add many new elements and attributes, many of which will not be in the appropriate DTD. This embedding causes validation against the DTD to fail. The obvious solution of changing or extending the DTD is not practical for most uses. This problem has been analyzed extensively by Sean B. Palmer in RDF in HTML: Approaches [RDF-IN-XHTML] and it concludes that there is no single embedding method that satisfies all applications and remains simple.
The recommended approach is to not embed RDF/XML in HTML/XHTML but
rather to use <link>
element in the <head>
element of the HTML/HTML to point at a separate RDF/XML document.
This approach has been used for several years by the
Dublin Core Metadata Initiative (DCMI)
on its Web site.
To use this technique, the <link>
element
href
should point at the URI of the RDF/XML content
and the type
attribute should be used with the value of
"application/rdf+xml"
, the proposed MIME type for
RDF/XML, see Section 4
The value of the rel
attribute may also be set to
indicate the relationship; this is an application dependent value.
The DCMI has used and recommended rel="meta"
when linking
in RFC 2731 — Encoding Dublin Core Metadata in HTML[RFC-2731] however
rel="alternate"
may also be appropriate.
See
HTML 4.01 link types,
XHTML Modularization — LinkTypes
and
XHTML 2.0 — LinkTypes
for further information on the values that may be appropriate
for the different versions of HTML.
Example 21 shows using this method with
the link
tag inside an XHTML document to link to an
external RDF/XML document.
link
in XHTML with an external RDF/XML document (example21.html linking to example21.rdf)<?xml version="1.0" encoding="utf-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <title>My document</title> <meta http-equiv="Content-type" content='text/html; charset="utf-8"' /> <link rel="alternate" type="application/rdf+xml" title="RDF Version" href="example21.rdf" /> </head> <body> <h1>My document</h1> </body> </html>
There is a standardized approach for associating RDF compatible metadata with SVG — the metadata element which was explicitly designed for this purpose as defined in Section 21 Metadata of the Scalable Vector Graphics (SVG) 1.0 Specification [SVG] and Section 21 Metadata of the Scalable Vector Graphics (SVG) 1.1 Specification [SVG11].
This document contains two example graphs in SVG with such embedded RDF/XML inside the metadata element: figure 1 and figure 2.
The following people provided valuable contributions to the document:
This document is a product of extended deliberations by the RDF Core working group, whose members have included: Art Barstow (W3C) Dave Beckett (ILRT), Dan Brickley (W3C/ILRT), Dan Connolly (W3C), Jeremy Carroll (Hewlett Packard), Ron Daniel (Interwoven Inc), Bill dehOra (InterX), Jos De Roo (AGFA), Jan Grant (ILRT), Graham Klyne (Clearswift and Nine by Nine), Frank Manola (MITRE Corporation), Brian McBride (Hewlett Packard), Eric Miller (W3C), Stephen Petschulat (IBM), Patrick Stickler (Nokia), Aaron Swartz (HWG), Mike Dean (BBN Technologies / Verizon), R. V. Guha (Alpiri Inc), Pat Hayes (IHMC), Sergey Melnik (Stanford University), Martyn Horner (Profium Ltd).
This specification also draws upon an earlier RDF Model and Syntax document edited by Ora Lassilla and Ralph Swick, and RDF Schema edited by Dan Brickley and R. V. Guha. RDF and RDF Schema Working group members who contributed to this earlier work are: Nick Arnett (Verity), Tim Berners-Lee (W3C), Tim Bray (Textuality), Dan Brickley (ILRT / University of Bristol), Walter Chang (Adobe), Sailesh Chutani (Oracle), Dan Connolly (W3C), Ron Daniel (DATAFUSION), Charles Frankston (Microsoft), Patrick Gannon (CommerceNet), RV Guha (Epinions, previously of Netscape Communications), Tom Hill (Apple Computer), Arthur van Hoff (Marimba), Renato Iannella (DSTC), Sandeep Jain (Oracle), Kevin Jones, (InterMind), Emiko Kezuka (Digital Vision Laboratories), Joe Lapp (webMethods Inc.), Ora Lassila (Nokia Research Center), Andrew Layman (Microsoft), Ralph LeVan (OCLC), John McCarthy (Lawrence Berkeley National Laboratory), Chris McConnell (Microsoft), Murray Maloney (Grif), Michael Mealling (Network Solutions), Norbert Mikula (DataChannel), Eric Miller (OCLC), Jim Miller (W3C, emeritus), Frank Olken (Lawrence Berkeley National Laboratory), Jean Paoli (Microsoft), Sri Raghavan (Digital/Compaq), Lisa Rein (webMethods Inc.), Paul Resnick (University of Michigan), Bill Roberts (KnowledgeCite), Tsuyoshi Sakata (Digital Vision Laboratories), Bob Schloss (IBM), 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.), Lauren Wood (SoftQuad).
application/rdf+xml
is archived at http://www.w3.org/2001/sw/RDFCore/mediatype-registration .
This appendix contains XML schemas for validating RDF/XML forms. These are example schemas for information only and are not part of this specification.
This is an example schema in RELAX NG Compact (for ease of reading) for RDF/XML. Applications can also use the RELAX NG XML version. These formats are described in RELAX NG ([RELAXNG]) and RELAX NG Compact ([RELAXNG-COMPACT]).
Note: The RNGC schema has been updated to attempt to match the grammar but this has not been checked or used to validate RDF/XML.
# # RELAX NG Compact Schema for RDF/XML Syntax # # This schema is for information only and NON-NORMATIVE # # It is based on one originally written by James Clark in # http://lists.w3.org/Archives/Public/www-rdf-comments/2001JulSep/0248.html # and updated with later changes. # namespace local = "" namespace rdf = "http://www.w3.org/1999/02/22-rdf-syntax-ns#" datatypes xsd = "http://www.w3.org/2001/XMLSchema-datatypes" start = doc # I cannot seem to do this in RNGC so they are expanded in-line # coreSyntaxTerms = rdf:RDF | rdf:ID | rdf:about | rdf:parseType | rdf:resource | rdf:nodeID | rdf:datatype # syntaxTerms = coreSyntaxTerms | rdf:Description | rdf:li # oldTerms = rdf:aboutEach | rdf:aboutEachPrefix | rdf:bagID # nodeElementURIs = * - ( coreSyntaxTerms | rdf:li | oldTerms ) # propertyElementURIs = * - ( coreSyntaxTerms | rdf:Description | oldTerms ) # propertyAttributeURIs = * - ( coreSyntaxTerms | rdf:Description | rdf:li | oldTerms ) # Also needed to allow rdf:li on all property element productions # since we can't capture the rdf:li rewriting to rdf_<n> in relaxng # Need to add these explicitly xmllang = attribute xml:lang { text } xmlbase = attribute xml:base { text } # and to forbid every other xml:* attribute, element doc = RDF | nodeElement RDF = element rdf:RDF { xmllang?, xmlbase?, nodeElementList } nodeElementList = nodeElement* # Should be something like: # ws* , ( nodeElement , ws* )* # but RELAXNG does this by default, ignoring whitespace separating tags. nodeElement = element * - ( local:* | rdf:RDF | rdf:ID | rdf:about | rdf:parseType | rdf:resource | rdf:nodeID | rdf:datatype | rdf:li | rdf:aboutEach | rdf:aboutEachPrefix | rdf:bagID ) { (idAttr | nodeIdAttr | aboutAttr )?, xmllang?, xmlbase?, propertyAttr*, propertyEltList } # It is not possible to say "and not things # beginning with _ in the rdf: namespace" in RELAX NG. ws = " " # Not used in this RELAX NG schema; but should be any legal XML # whitespace defined by http://www.w3.org/TR/2000/REC-xml-20001006#NT-S propertyEltList = propertyElt* # Should be something like: # ws* , ( propertyElt , ws* )* # but RELAXNG does this by default, ignoring whitespace separating tags. propertyElt = resourcePropertyElt | literalPropertyElt | parseTypeLiteralPropertyElt | parseTypeResourcePropertyElt | parseTypeCollectionPropertyElt | parseTypeOtherPropertyElt | emptyPropertyElt resourcePropertyElt = element * - ( local:* | rdf:RDF | rdf:ID | rdf:about | rdf:parseType | rdf:resource | rdf:nodeID | rdf:datatype | rdf:Description | rdf:aboutEach | rdf:aboutEachPrefix | rdf:bagID | xml:* ) { idAttr?, xmllang?, xmlbase?, nodeElement } literalPropertyElt = element * - ( local:* | rdf:RDF | rdf:ID | rdf:about | rdf:parseType | rdf:resource | rdf:nodeID | rdf:datatype | rdf:Description | rdf:aboutEach | rdf:aboutEachPrefix | rdf:bagID | xml:* ) { (idAttr | datatypeAttr )?, xmllang?, xmlbase?, text } parseTypeLiteralPropertyElt = element * - ( local:* | rdf:RDF | rdf:ID | rdf:about | rdf:parseType | rdf:resource | rdf:nodeID | rdf:datatype | rdf:Description | rdf:aboutEach | rdf:aboutEachPrefix | rdf:bagID | xml:* ) { idAttr?, parseLiteral, xmllang?, xmlbase?, literal } parseTypeResourcePropertyElt = element * - ( local:* | rdf:RDF | rdf:ID | rdf:about | rdf:parseType | rdf:resource | rdf:nodeID | rdf:datatype | rdf:Description | rdf:aboutEach | rdf:aboutEachPrefix | rdf:bagID | xml:* ) { idAttr?, parseResource, xmllang?, xmlbase?, propertyEltList } parseTypeCollectionPropertyElt = element * - ( local:* | rdf:RDF | rdf:ID | rdf:about | rdf:parseType | rdf:resource | rdf:nodeID | rdf:datatype | rdf:Description | rdf:aboutEach | rdf:aboutEachPrefix | rdf:bagID | xml:* ) { idAttr?, xmllang?, xmlbase?, parseCollection, nodeElementList } parseTypeOtherPropertyElt = element * - ( local:* | rdf:RDF | rdf:ID | rdf:about | rdf:parseType | rdf:resource | rdf:nodeID | rdf:datatype | rdf:Description | rdf:aboutEach | rdf:aboutEachPrefix | rdf:bagID | xml:* ) { idAttr?, xmllang?, xmlbase?, parseOther, any } emptyPropertyElt = element * - ( local:* | rdf:RDF | rdf:ID | rdf:about | rdf:parseType | rdf:resource | rdf:nodeID | rdf:datatype | rdf:Description | rdf:aboutEach | rdf:aboutEachPrefix | rdf:bagID | xml:* ) { idAttr?, (resourceAttr | nodeIdAttr)?, xmllang?, xmlbase?, propertyAttr* } idAttr = attribute rdf:ID { IDsymbol } nodeIdAttr = attribute rdf:nodeID { IDsymbol } aboutAttr = attribute rdf:about { URI-reference } propertyAttr = attribute * - ( local:* | rdf:RDF | rdf:ID | rdf:about | rdf:parseType | rdf:resource | rdf:nodeID | rdf:datatype | rdf:li | rdf:Description | rdf:aboutEach | rdf:aboutEachPrefix | rdf:bagID | xml:* ) { string } resourceAttr = attribute rdf:resource { URI-reference } datatypeAttr = attribute rdf:datatype { URI-reference } parseLiteral = attribute rdf:parseType { "Literal" } parseResource = attribute rdf:parseType { "Resource" } parseCollection = attribute rdf:parseType { "Collection" } parseOther = attribute rdf:parseType { text } URI-reference = string literal = any IDsymbol = xsd:NMTOKEN any = mixed { element * { attribute * { text }*, any }* }
Changes since 10 October 2003 second last call working draft
These are are divided into non-editorial and editorial. The non-editorial changes also list consquential editorial changes. Editorial changes are those which do not result in any change in the meaning of an RDF document or the behaviour of an RDF application.
None
rdf:parseType="Resource"
as pointed out by
comment by Sabadello 2003-10-30
rdf:type
casesNone