--- a/rdf-mt/index.html Thu Dec 12 02:10:15 2013 -0800
+++ b/rdf-mt/index.html Thu Dec 12 09:48:37 2013 -0800
@@ -511,8 +511,7 @@
<p>The exact mechanism by which an IRI <a title="identify">identifies</a> a datatype IRI is considered to be external to the semantics, but the semantics presumes that a recognized IRI <a title="identify">identifies</a> a unique datatype wherever it occurs. RDF processors which are not able to determine which datatype is identified by an IRI cannot <a>recognize</a> that IRI, and should treat any literals with that IRI as their datatype IRI as unknown names. </p>
-<p>RDF literals and datatypes are fully described in <a href="http://www.w3.org/TR/rdf11-concepts/#section-Datatypes"> Section 5</a> of [[!RDF11-CONCEPTS]]. In summary: RDF literals are either language-tagged strings, or literals which
-combine a string and an IRI <a>identify</a>ing a datatype. A datatype is understood to define a partial mapping, called the <dfn>lexical-to-value mapping</dfn>, from a lexical space (a set of character strings) to values. The function <dfn>L2V</dfn> maps datatypes to their lexical-to-value mapping. A literal with datatype d denotes the value obtained by applying this mapping to the character string sss: L2V(d)(sss). If the literal string is not in the lexical space, so that the lexical-to-value mapping gives no value for the literal string, then the literal has no referent. The <dfn>value space</dfn> of a datatype is the range of the <a>lexical-to-value mapping</a>. Every literal with that type either refers to a value in the value space of the type, or fails to refer at all. An <dfn>ill-typed</dfn> literal is one whose datatype IRI is <a>recognize</a>d, but whose character string is assigned no value by the <a>lexical-to-value mapping</a> for that datatype. </p>
+<p>RDF literals and datatypes are fully described in <a href="http://www.w3.org/TR/rdf11-concepts/#section-Datatypes"> Section 5</a> of [[!RDF11-CONCEPTS]]. In summary: with one exception, RDF literals combine a string and an IRI <a>identify</a>ing a datatype. The exception is <a href="http://www.w3.org/TR/rdf11-concepts/#dfn-language-tagged-string">language-tagged strings</a>, which have two syntactic components, a string and a language tag, and are assigned the type <code>rdf:langString</code>. A datatype is understood to define a partial mapping, called the <dfn>lexical-to-value mapping</dfn>, from a lexical space (a set of character strings) to values. The function <dfn>L2V</dfn> maps datatypes to their lexical-to-value mapping. A literal with datatype d denotes the value obtained by applying this mapping to the character string sss: L2V(d)(sss). If the literal string is not in the lexical space, so that the lexical-to-value mapping gives no value for the literal string, then the literal has no referent. The <dfn>value space</dfn> of a datatype is the range of the <a>lexical-to-value mapping</a>. Every literal with that type either refers to a value in the value space of the type, or fails to refer at all. An <dfn>ill-typed</dfn> literal is one whose datatype IRI is <a>recognize</a>d, but whose character string is assigned no value by the <a>lexical-to-value mapping</a> for that datatype. </p>
<p> RDF processors are not required to <a>recognize</a> any datatype IRIs other than <a href="http://www.w3.org/TR/rdf11-concepts/#dfn-language-tagged-string"><code>rdf:langString</code></a> and <a href="http://www.w3.org/TR/xmlschema11-2/#string"><code>xsd:string</code></a>, but when IRIs listed in <a href="http://www.w3.org/TR/rdf11-concepts/#section-Datatypes">Section 5</a> of [[!RDF11-CONCEPTS]] are <a>recognize</a>d, they MUST be interpreted as described there, and when the IRI <code>rdf:PlainLiteral</code> is <a>recognize</a>d, it MUST be interpreted to refer to the datatype defined in [[!RDF-PLAIN-LITERAL]]. RDF processors MAY recognize other datatype IRIs, but when other datatype IRIs are <a>recognize</a>d, the mapping between the datatype IRI and the datatype it refers to 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 <a>datatype map</a> of this IRI.</p>