RDF 1.2 XML Syntax

Constructed from a document information item and takes the following accessors and values.

document-element

Set to the value of document information item property [document-element].

children

Set to the value of document information item property [children].

base-iri

Set to the value of document information item property [base IRI].

language

Set to the empty string.

direction

Set to the empty string.

graph

The graph used for collecting emitted triples, initialized to a new RDF graph.

Constructed from an element information item and takes the following accessors and values:

local-name

Set to the value of element information item property [local name].

namespace-name

Set to the value of element information item property [namespace name].

children

Set to the value of element information item property [children].

parent

Set to the value of element information item property [parent].

base-iri

Set to the value of element information item property [base IRI].

attributes

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 "https://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.

If the element has a version accessor with the value "1.2-basic", "1.2" or greater, this set contains an attribute information item its:dir ([namespace name] property with the value "https://www.w3.org/2005/11/its" and [local name] property value "dir") it is removed from the set of attribute information items and the ·direction· accessor is set to the [normalized-value] property of the attribute information item, which MUST be one of "ltr", "rtl", or the empty string.

If the element has a version accessor with the value "1.2-basic", "1.2" or greater, this set contains an attribute information item its:version ([namespace name] property with the value "https://www.w3.org/2005/11/its" and [local name] property value "version") it is removed from the set of attribute information items and the ·its-version· accessor is set to the [normalized-value] property of the attribute information item.

All remaining reserved XML Names (see Name in Extensible Markup Language (XML) 1.1 (Second Edition)) 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 IRI] 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.

IRI

Set to an IRI constructed from the concatenation of the value of the namespace-name accessor and the value of the local-name accessor.

li-counter

Set to the integer value 1.

language

Set from the ·attributes· as described above. If no value is given from the attributes, the value is set to the value of the language accessor on the parent event (either a Root Event or an Element Event), which may be the empty string.

direction

Set from the ·attributes· as described above. If no value is given from the attributes, the value is set to the value of the direction accessor on the parent event (either a Root Event or an Element Event), which may be the empty string.

version

Set from the ·attributes· as described above. If no value is given from the attributes, the value is set to the value of the version accessor on the parent event (either a Root Event or an Element Event).

its-version

Set from the ·attributes· as described above. If no value is given from the attributes, the value is set to the value of the version accessor on the parent event (either a Root Event or an Element Event), which SHOULD be set to "2.0".

subject

Has no initial value. Takes a value that is an Identifier event, or a triple term. This accessor is used on elements that deal with one node in the RDF graph, this generally being the subject of an RDF triple.

graph

The graph used for collecting emitted triples. The initial value is taken from the parent event (either a Root Event or an Element Event), or a new RDF graph, if not set. May be modified by a parseType="Triple" attribute.

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:

local-name

Set to the value of attribute information item property [local name].

namespace-name

Set to the value of attribute information item property [namespace name].

string-value

Set to the value of the attribute information item property [normalized value] as specified by [XML11] (if an attribute whose normalized value is a zero-length string, then the string-value is also a zero-length string).

IRI

If ·namespace-name· is present, set to an IRI constructed from 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, parseType, resource, type, or version, set to an IRI constructed from the value of the concatenation of the RDF namespace IRI 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-SYNTAX-GRAMMAR-19990222] 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 IRIs from XML attributes can generate the same IRIs 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.

rdf-term

The value is an IRI constructed from string-value resolved against the ·base-iri· accessor of the containing element.

Constructed from a sequence of one or more consecutive character information items. Has the single accessor:

string-value

Set to the value of the string made from concatenating the [character code] property of each of the character information items.

An event for an IRI which has the following accessors:

identifier

Takes a string value used as an IRI.

rdf-term

The value is an IRI constructed from the value of the ·identifier· accessor.

These events are constructed by giving a value for the ·identifier· accessor.

For further information on identifiers in RDF, see 4.2 Identifiers.

An event for an triple term which has the following accessors:

rdf-term

The value is a triple term.

These events are constructed by giving a value to the rdf-term accessor.

An event for a blank node identifier which has the following accessors:

identifier

Takes a string value.

blank-node

The value is a blank node with local identifier taken from the ·identifier· accessor. Within an RDF/XML document, all blank nodes identified by the same identifier represent the same blank node.

These events are constructed by giving a value for the ·identifier· accessor.

For further information on identifiers in RDF, see 4.2 Identifiers.

An event for a literal without an explicit datatype which can have the following accessors:

literal-value

Takes a string value.

literal-language

Takes a string value used as a language tag in language-tagged string.

literal-direction

Takes a string value used as a direction tag in a directional language-tagged strings.

literal

The value is an RDF literal constructed from the other accessors as follows.

If ·literal-language· is the empty string then the value is an RDF literal with the lexical form taken from the value of the ·literal-value· accessor and datatype IRI xsd:string.

Otherwise, if the ·literal-direction· is the empty string, then the value is a language-tagged string with the lexical form taken from the value of the ·literal-value· accessor and the language tag taken from the value of the ·literal-language· accessor.

Otherwise the value is a directional language-tagged string with the lexical form taken from the value of the ·literal-value· accessor, the language tag taken from the value of the ·literal-language· accessor, and the base direction taken from the value of the ·literal-direction· accessor.

These events are constructed by giving values for the ·literal-value·, ·literal-language·, and ·literal-direction· accessors.

An event for a typed literal which can have the following accessors:

literal-value

Takes a string value.

literal-datatype

Takes a string value used as an IRI.

literal

The value is an RDF literal with the lexical form taken from the value of the ·literal-value· accessor and datatype IRI taken from the value of the ·literal-datatype· accessor.

These events are constructed by giving values for the ·literal-value· and ·literal-datatype· accessors.

If the RDF/XML is a standalone XML document (identified by presentation as an application/rdf+xml RDF media 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-iri· 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.

The start node is referred to as the top-level XML document element.

A subset of the syntax terms from the RDF Vocabulary in 4.1 The RDF Namespace and Vocabulary which are used in RDF/XML.

All the syntax terms from the RDF Vocabulary in 4.1 The RDF Namespace and Vocabulary which are used in RDF/XML.

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.

The IRIs that are allowed on node elements.

The URIs that are allowed on property elements.

The IRIs that are allowed on property attributes.

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:

• If there is an attribute a with a.IRI == rdf:ID, then e.subject := iri(identifier := resolve(e, concat("#", a.string-value))).
• If there is an attribute a with a.IRI == rdf:nodeID, then e.subject := bnodeid(identifier:=a.string-value).
• If there is an attribute a with a.IRI == rdf:about then e.subject := iri(identifier := e.rdf-term).

If e.subject is empty, then e.subject := bnodeid(identifier := generated-blank-node-id()).

The following can then be performed in any order:

• If e.IRI != rdf:Description then the following statement is added to e.parent.graph:

  e.subject.rdf-term <https://www.w3.org/1999/02/22-rdf-syntax-ns#type> e.IRI .

• If there is an attribute a in propertyAttr with a.IRI == rdf:type then u:=iri(identifier:=e.rdf-term) and the following triple is e.parent.graph:

  e.subject.rdf-term <https://www.w3.org/1999/02/22-rdf-syntax-ns#type> u.rdf-term .

• For each attribute a matching propertyAttr (and not 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, literal-direction := e.direction) and the following statement is added to e.parent.graph:

  e.subject.rdf-term a.IRI o.literal .

• Handle the propertyEltList children events in document order.

If element e has e.IRI = rdf:li then apply the list expansion rules on element e.parent in 6.4 List Expansion Rules to give a new IRI u and e.IRI := 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.

For element e, and the single contained nodeElement n, first n MUST be processed using production nodeElement. Then the following statement is added to e.parent.graph:

If the rdf:ID attribute a is given, the above statement is reified with i := iri(identifier := resolve(e, concat("#", a.string-value))) using the reification rules in 6.3 Reification Rules and e.subject := i

If either the rdf:annotation or rdf:annotationNodeID attributes a are given, the statement above is used to create a triple term t, and the following statement is added to e.parent.graph:

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.rdf-term) otherwise o := literal(literal-value := t.string-value, literal-language := e.language, literal-direction := e.direction) and the following statement is added to e.parent.graph:

If the rdf:ID attribute a is given, the above statement is reified with i := iri(identifier := resolve(e, concat("#", a.string-value))) using the reification rules in 6.3 Reification Rules and e.subject := i.

If either the rdf:annotation or rdf:annotationNodeID attributes a are given, the statement above is used to create a triple term t, and the following statement is added to e.parent.graph:

For element e with possibly empty element content c.

n := bnodeid(identifier := generated-blank-node-id()).

Add the following statement to e.parent.graph:

If the rdf:ID attribute a is given, the statement above is reified with i := iri(identifier := resolve(e, concat("#", a.string-value))) using the reification rules in 6.3 Reification Rules and e.subject := i.

If either the rdf:annotation or rdf:annotationNodeID attributes a are given, the statement above is used to create a triple term t, and the following statement is added to e.parent.graph:

If the element content c is not empty, then use event n to create a new sequence of events as follows:

Then process the resulting sequence using production nodeElement.

For element e with element content c.

Create a new sequence of events as follows:

Then process the resulting sequence using production nodeElement.

After processing the node sequence, e.parent.graph MUST be an RDF graph containing a single triple.

e.subject := triple(s, p, o), where s, p, and o are the subject, predicate, and object of the sole triple in e.parent.graph.

Add the following statement added to e.parent.graph:

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 e.parent.graph:

otherwise the following statement is added to e.parent.graph:

If the rdf:ID attribute a is given, either of the the above statements is reified with i := iri(identifier := resolve(e, concat("#", a.string-value))) using the reification rules in 6.3 Reification Rules.

If either the rdf:annotation or rdf:annotationNodeID attributes a are given, the statement above is used to create a triple term t, and the following statement is added to e.parent.graph:

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 e.parent.graph:

For each consecutive and overlapping pair of events (n, o) in s, the following statement is added to e.parent.graph:

If s is not empty, n is the last event identifier in s, the following statement is added to e.parent.graph:

All rdf:parseType attribute values other than the strings "Resource", "Literal", "Collection", or "Triple" 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.

• If there are no attributes or only the optional rdf:ID attribute i, or the optional attributes rdf:annotation or rdf:annotationNodeID a, then o := literal(literal-value:="", literal-language := e.language, literal-direction := e.direction) and the following statement is added to e.parent.graph:

  e.parent.subject.rdf-term e.IRI o.literal .

  and then if i is given, the above statement is reified with iri(identifier := resolve(e, concat("#", i.string-value))) using the reification rules in 6.3 Reification Rules.

  and then if a is given, the statement above is used to create a triple term t, and the following statement is added to e.parent.graph:

     a.rdf-term <https://www.w3.org/1999/02/22-rdf-syntax-ns#reifies> t.rdf-term .

• Otherwise

  • If rdf:resource attribute i is present, then r := iri(identifier := i.rdf-term)
  • If rdf:nodeID attribute i is present, then r := bnodeid(identifier := i.string-value)
  • If neither, r := bnodeid(identifier := generated-blank-node-id())

  The following are done in any order:

  • For all propertyAttr attributes a (in any order)

    • If a.IRI == rdf:type then u:=iri(identifier:=i.rdf-term) and the following triple is added to e.parent.graph:

      r.rdf-term <https://www.w3.org/1999/02/22-rdf-syntax-ns#type> u.rdf-term .

    • Otherwise Unicode string a.string-value SHOULD be in Normal Form C [NFC], o := literal(literal-value := a.string-value, literal-language := e.language, literal-direction := e.direction) and the following statement is added to e.parent.graph:

      r.rdf-term a.IRI o.literal .

  • Add the following statement to the graph:

    e.parent.subject.rdf-term e.IRI r.rdf-term .

    and then if rdf:ID attribute i is given, the above statement is reified with iri(identifier := resolve(e, concat("#", i.rdf-term))) using the reification rules in 6.3 Reification Rules.

    and then if either the rdf:annotation or rdf:annotationNodeID attributes a are given, the statement above is used to create a triple term t, and the following statement is added to e.parent.graph:

       a.rdf-term <https://www.w3.org/1999/02/22-rdf-syntax-ns#reifies> t.rdf-term .

Constraint:: constraint-id applies to the values of rdf:ID attributes

This production MAY be ignored unless rdf:version is "1.2" or greater.

This production MAY be ignored unless rdf:version is "1.2" or greater.