Primitive data type "anyURI" of the XML Schema data types. Definition from XML Schema Part 2: Datatypes Second Edition: "anyURI" represents a Uniform Resource Identifier Reference (URI). An "anyURI" value can be absolute or relative, and may have an optional fragment identifier (i.e., it may be a URI Reference). This type should be used to specify the intention that the value fulfills the role of a URI as defined by [RFC 2396], as amended by [RFC 2732]. For details see https://www.w3.org/TR/xmlschema-2/#anyURI.