<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
    xmlns:this="www.example.org/attrib/enum"
    targetNamespace="www.example.org/attrib/enum">

<xsd:complexType name="AttribEnum">
	<xsd:attribute name="attr">
		<xsd:simpleType>
			<xsd:restriction base="xsd:string">
				<xsd:enumeration value="first"/>
				<xsd:enumeration value="second"/>
			</xsd:restriction>
		</xsd:simpleType>
	</xsd:attribute>
</xsd:complexType>

</xsd:schema>

