This should help you on your way
<xs:schema id="Alpha" xmlns:xs="#unknown">
targetNamespace="http://tempuri.org/Alpha.xsd"
elementFormDefault="qualified"
xmlns="http://tempuri.org/Alpha.xsd"
xmlns:mstns="http://tempuri.org/Alpha.xsd"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
>
<xs:element name="Artwork">
<xs:complextype>
<xs:attribute name="ID" type="ArtworkType" />
</xs:complextype>
</xs:element>
<xs:simpletype name="ArtworkType">
<xs:restriction base="xs:integer">
<xs:mininclusive value="0" />
<xs:maxinclusive value="100" />
</xs:restriction>
</xs:simpletype>
</xs:schema>