Nearby: IRI Edit Overview
This is a survey of the use of IRIs and variants in W3C specs, carried out in Summer 2007 in the course of updating RFC 3987. The survey is mostly structured by Domain/Activity.
System Identifiers: The grammar production allows any character. However, general C0 control codes are excluded, because they are not allowed in XML 1.0, and because in XML 1.1, they would need numeric character references and these are not allowed in System Identifiers.
 SystemLiteral ::= ('"' [^"]* '"') | ("'" [^']* "'")
Within this specification, the term URI refers to a Universal Resource Identifier as defined in [RFC3986] and extended in [RFC3987] with the new name IRI. The term URI has been retained in preference to IRI to avoid introducing new names for concepts such as "Base URI" that are defined or referenced across the whole family of XML specifications.
EMMA: see http://www.w3.org/International/reviews/0704-emma/, comment 7
RDF Primer, Appendix A: More on Uniform Resource Identifiers (URIs): "RDF URIrefs can contain Unicode [UNICODE] characters (see [RDF-CONCEPTS]), allowing many languages to be reflected in URIrefs."; references RFC 2396 (i.e. pre RFC 3986/7).
RDF Concepts and Abstract Syntax, Section 6.4, RDF URI References (Feb 2004): Circumscribing definition, most probably identical to XML (needs detail check); several very interesting notes ([IRI draft] references draft-duerst-iri-04):
Note: RDF URI references are compatible with the anyURI datatype as defined by XML schema datatypes [XML-SCHEMA2], constrained to be an absolute rather than a relative URI reference.
Note: RDF URI references are compatible with International Resource Identifiers as defined by [XML Namespaces 1.1].
Note: this section anticipates an RFC on Internationalized Resource Identifiers. Implementations may issue warnings concerning the use of RDF URI References that do not conform with [IRI draft] or its successors.