diff --git a/spec/index.html b/spec/index.html index 9d525b6..34e620c 100644 --- a/spec/index.html +++ b/spec/index.html @@ -418,9 +418,11 @@

Simple Interpretations

Usage has shown that it is important that every literal have a type. RDF 1.1 replaces plain literals without language tags by literals typed with the XML Schema string datatype, - and introduces the special type rdf:langString + and introduces the special type + rdf:langString for language-tagged strings. - The full semantics for typed literals is given in the next section.

+ The full semantics for typed literals is given in section [[[#datatypes]]]. +

Simple interpretations are required to interpret all names, @@ -751,13 +753,14 @@

Literals and datatypes

RDF literals and datatypes are fully described in Section 5 of [[!RDF12-CONCEPTS]]. - In summary: with one exception, RDF literals combine a string and an IRI identifing a datatype. - The exception is language-tagged strings, - which have two syntactic components, a string and a language tag, - and are assigned the type rdf:langString. - A datatype is understood to define a partial mapping, - called the - + In summary: with two exceptions, RDF literals combine a string and an IRI identifying a datatype. + The exceptions are language-tagged strings, assigned the type rdf:langString, + which have two syntactic components, a string and a language tag; and + directional language-tagged strings, + assigned the type rdf:dirLangString, + which have three syntactic components, a string, a language tag, and a base direction. + A datatype is understood to define a partial mapping, called the + lexical-to-value mapping, from a lexical space (a set of character strings) to values. The function L2V maps datatypes to their lexical-to-value mapping. @@ -774,18 +777,38 @@

Literals and datatypes

for that datatype.

RDF processors are not required to recognize any datatype IRIs other than - rdf:langString - and xsd:string, + xsd:string, + rdf:langString, and + rdf:dirLangString but when IRIs listed in Section 5 of [[!RDF12-CONCEPTS]] - are recognized, they MUST be interpreted as described there, and when the IRI rdf:PlainLiteral is recognized, it MUST be interpreted to denote the datatype defined in [[!RDF-PLAIN-LITERAL]]. RDF processors MAY recognize other datatype IRIs, but when other datatype IRIs are recognized, the mapping between the datatype IRI and the datatype it denotes MUST be specified unambiguously, and MUST be fixed during all RDF transformations or manipulations. In practice, this can be achieved by the IRI linking to an external specification of the datatype which describes both the components of the datatype itself and the fact that the IRI identifies the datatype, thereby fixing a value of the datatype map of this IRI.

+ are recognized, they MUST be interpreted as described there, and + when the IRI rdf:PlainLiteral is recognized, + it MUST be interpreted to denote the datatype defined in [[!RDF-PLAIN-LITERAL]]. + RDF processors MAY recognize other datatype IRIs, + but when other datatype IRIs are recognized, + the mapping between the datatype IRI and the datatype it denotes + MUST be specified unambiguously, + and MUST be fixed during all RDF transformations or manipulations. + In practice, this can be achieved by the IRI linking + to an external specification of the datatype + which describes both the components of the datatype itself + and the fact that the IRI identifies the datatype, + thereby fixing a value of the datatype map of this IRI.

Literals with rdf:langString - as their datatype are an exceptional case which are given a special treatment. - The IRI rdf:langString is classified as a datatype IRI, - and interpreted to denote a datatype, even though no L2V mapping is defined for it. - The value space of rdf:langString is the set of all pairs of a string with a language tag. - The semantics of literals with this as their type are given below.

+ or rdf:dirLangString + as their datatype IRI are given special treatment. + The IRIs rdf:langString and rdf:dirLangString + are classified as datatype IRIs and interpreted to denote a datatype, + even though no L2V mapping is defined for them. + The value space of rdf:langString + is the set of all pairs of a string with a language tag. + The value space of rdf:dirLangString + is the set of all + 3-tuples of a string, a language tag, and a base direction. + The semantics of literals with either of these as their datatype are given below. +

RDF allows any IRI to be used in a literal, even when it is not recognized as referring to a datatype. @@ -816,7 +839,10 @@

D-interpretations

If rdf:langString is in D, then for every language-tagged string E with lexical form sss and language tag ttt, IL(E)= < sss, ttt' >, where ttt' is ttt converted to lower case using US-ASCII rules - + If rdf:dirLangString is in D, + then for every directional language-tagged string E with lexical form sss, + language tag ttt, and base direction bbb, + IL(E)= < sss, ttt', bbb >, where ttt' is ttt converted to lower case using US-ASCII rules For every other IRI aaa in D, I(aaa) is the datatype identified by aaa, and for every literal "sss"^^aaa, IL("sss"^^aaa) = L2V(I(aaa))(sss) @@ -832,10 +858,12 @@

D-interpretations

literals with an unrecognized type IRI are not ill-typed and cannot give rise to a D-unsatisfiable graph.

-

The special datatype rdf:langString - has no ill-typed literals. - Any syntactically legal literal with this type will denote a value in every - D-interpretation where D includes rdf:langString. +

The special datatypes + rdf:langString and + rdf:dirLangString + have no ill-typed literals. + Any syntactically legal literal with one of these types will denote a value in every + D-interpretation where D includes rdf:langString or rdf:dirLangString. The only ill-typed literals of type xsd:string are those containing a Unicode code point which does not match the Char production in [[XML11]]. @@ -845,7 +873,6 @@

D-interpretations

ill-typed literals were required to denote a value in IR, and D-unsatisfiability could be recognized only by using the RDFS semantics.

-
@@ -932,14 +959,14 @@

RDF Interpretations

rdf:type rdf:subject rdf:predicate rdf:object rdf:first rdf:rest rdf:value rdf:nil - rdf:List rdf:langString rdf:Property rdf:_1 rdf:_2 + rdf:List rdf:langString rdf:dirLangString rdf:Property rdf:_1 rdf:_2 ...

An RDF interpretation recognizing D is a D-interpretation I - where D includes rdf:langString and xsd:string, and which satisfies:

+ where D includes rdf:langString, rdf:dirLangString, and xsd:string, and which satisfies:

@@ -977,12 +1004,16 @@

RDF Interpretations

RDF imposes no particular normative meanings on the rest of the RDF vocabulary. Appendix D describes the intended uses of some of this vocabulary.

-

The datatype IRIs rdf:langString +

The datatype IRIs + rdf:langString, + rdf:dirLangString, and xsd:string MUST be recognized by all RDF interpretations.

-

Two other datatypes rdf:XMLLiteral - and rdf:HTML are defined in [[!RDF12-CONCEPTS]]. +

Three other datatypes — rdf:XMLLiteral, + rdf:HTML, and + rdf:JSON — + are defined in [[!RDF12-CONCEPTS]]. RDF-D interpretations MAY fail to recognize these datatypes.

@@ -990,7 +1021,8 @@

RDF entailment

S RDF entails E recognizing D when every RDF interpretation recognizing D which satisfies - S also satisfies E. When D is {rdf:langString, xsd:string} + S also satisfies E. When D is {rdf:langString, + rdf:dirLangString, xsd:string} then we simply say S RDF entails E. E is RDF unsatisfiable (recognizing D) when it has no satisfying RDF interpretation (recognizing D).

@@ -1146,6 +1178,7 @@

RDFS Interpretations

LV is defined to be ICEXT(I(rdfs:Literal))

ICEXT(I(rdfs:Resource)) = IR

ICEXT(I(rdf:langString)) is the set {I(E) : E a language-tagged string }

+

ICEXT(I(rdf:dirLangString)) is the set {I(E) : E a directional language-tagged string }

for every other IRI aaa in D, ICEXT(I(aaa)) is the value space of I(aaa)

for every IRI aaa in D, I(aaa) is in ICEXT(I(rdfs:Datatype))

@@ -1610,7 +1643,8 @@

Entailment rules (Informative)

  • If no triples were added in step 2, add the RDF (and RDFS) axiomatic triples which contain rdf:_1.
  • For every IRI or literal aaa used in E, add aaa rdf:type rdfs:Resource to S.
  • Apply the rules GrdfD1, rdfD1a, and rdfD2 (and the rules rdfs1 through rdfs13), - with D={rdf:langString, xsd:string}, to the set in all possible ways, to exhaustion.
    • + with D={rdf:langString, rdf:dirLangString, xsd:string}, + to the set in all possible ways, to exhaustion.

    Then we have the completeness result:

    @@ -2063,7 +2097,12 @@

    Acknowledgments

    Substantive changes since RDF 1.1

    RDF semantic conditions.