See http://www.w3.org/XML/1998/namespace.html and
http://www.w3.org/TR/REC-xml for information about this namespace.This schema defines attributes and an attribute group
suitable for use by
schemas wishing to allow xml:base, xml:lang or xml:space attributes
on elements they define.
To enable this, such a schema must import this schema
for the XML namespace, e.g. as follows:
<schema . . .>
. . .
<import namespace="http://www.w3.org/XML/1998/namespace"
schemaLocation="http://www.w3.org/2001/03/xml.xsd"/>
Subsequently, qualified reference to any of the attributes
or the group defined below will have the desired effect, e.g.
<type . . .>
. . .
<attributeGroup ref="xml:specialAttrs"/>
will define a type which will schema-validate an instance
element with any of those attributesIn keeping with the XML Schema WG's standard versioning
policy, this schema document will persist at
http://www.w3.org/2001/03/xml.xsd.
At the date of issue it can also be found at
http://www.w3.org/2001/xml.xsd.
The schema document at that URI may however change in the future,
in order to remain compatible with the latest version of XML Schema
itself. In other words, if the XML Schema namespace changes, the version
of this document at
http://www.w3.org/2001/xml.xsd will change
accordingly; the version at
http://www.w3.org/2001/03/xml.xsd will not change.