XML Schema

Name

xs:anyURI — URI (Uniform Resource Identifier).

Derived from:

xs:anySimpleType

Primary:

xs:anyURI

Known subtypes:

none

Facets:

xs:enumeration, xs:length, xs:maxLength, xs:minLength, xs:pattern, xs:whiteSpace

<xs:simpleType name="anyURI" id="anyURI">
  <xs:restriction base="xs:anySimpleType">
    <xs:whiteSpace value="collapse" fixed="true"/>
  </xs:restriction></xs:simpleType>

Description

This datatype corresponds normatively to the XLink href attribute. Its value space includes the URIs defined by the RFCs 2396 and 2732, but its lexical space doesn’t require the character escapes needed to include non-ASCII characters in URIs.

Restrictions

Relative URIs are not “absolutized” by W3C XML Schema. A datatype defined as:

<xs:simpleType name="schemaRecommendations">
  <xs:restriction base="xs:anyURI">
    <xs:enumeration value="http://www.w3.org/TR/xmlschema-0/"/>
    <xs:enumeration value="http://www.w3.org/TR/xmlschema-1/"/>
    <xs:enumeration value="http://www.w3.org/TR/xmlschema-2/"/>
  </xs:restriction> 
</xs:simpleType>

should not validate the href attribute in this instance element:

<a xml:base="http://www.w3.org/TR/" href="xmlschema-1/">
  XML Schema Part 2: Datatypes
</a>

The Recommendation states that “it is impractical for processors to check that a value is a context-appropriate URI reference,” freeing schema processors from having to validate the correctness of the URI.

Example

<xs:simpleType name="httpURI"> <xs:restriction base="xs:anyURI"> <xs:pattern value="http://.*"/> </xs:restriction> </xs:simpleType> ...