<?xml version='1.0'?>
<xs:schema targetNamespace="http://www.w3.org/XML/1998/namespace" xmlns:xs="http://www.w3.org/2001/XMLSchema" xml:lang="en">

 <xs:annotation>
  <xs:documentation>This schema defines attributes and an attribute group
        suitable for use by
        schemas wishing to allow 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:
        &lt;schema . . .>
         . . .
         &lt;import namespace="http://www.w3.org/XML/1998/namespace"
                    schemaLocation="http://www.w3.org/2001/03/xml.xsd"/>

        Subsequently, qualified reference to either of the attributes
        or the group defined below will have the desired effect, e.g.

        &lt;type . . .>
         . . .
         &lt;attributeGroup ref="xml:specialAttrs"/>
 
         will define a type which will schema-validate a instance
         element with both xml:space and xml:lang attribute</xs:documentation>
 </xs:annotation>

 <xs:attribute name="lang" type="xs:language">
  <xs:annotation>
   <xs:documentation>In due course, we should install the relevant ISO 2- and 3-letter
         codes as the enumerated possible values . . .</xs:documentation>
  </xs:annotation>
 </xs:attribute>

 <xs:attribute name="space" default="preserve">
  <xs:simpleType>
   <xs:restriction base="xs:NCName">
    <xs:enumeration value="default"/>
    <xs:enumeration value="preserve"/>
   </xs:restriction>
  </xs:simpleType>
 </xs:attribute>

 <xs:attributeGroup name="specialAttrs">
  <xs:attribute ref="xml:lang"/>
  <xs:attribute ref="xml:space"/>
 </xs:attributeGroup>

</xs:schema>
