1  <?xml version="1.0"?>
 2  <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
 3    <xsd:element name="comment" type="xsd:string"/>
 4  <!-- Stock Keeping Unit, a code for identifying products -->
 5    <xsd:simpleType name="SKU">
 6      <xsd:restriction base="xsd:string">
 7        <xsd:pattern value="\d{3}-[A-Z]{2}"/>
 8      </xsd:restriction>
 9    </xsd:simpleType>
10    <xsd:element name="Item">
11      <xsd:complexType>
12        <xsd:sequence>
13          <xsd:element name="productName" type="xsd:string"/>
14          <xsd:element name="quantity">
15            <xsd:simpleType>
16              <xsd:restriction base="xsd:positiveInteger">
17                <xsd:maxExclusive value="100"/>
18              </xsd:restriction>
19            </xsd:simpleType>
20          </xsd:element>
21          <xsd:element name="USPrice" type="xsd:decimal"/>
22          <xsd:element ref="comment" minOccurs="0"/>
23          <xsd:element name="shipDate" type="xsd:date" minOccurs="0"/>
24        </xsd:sequence>
25  <!-- attributeGroup replaces individual declarations -->
26        <xsd:attributeGroup ref="ItemDelivery"/>
27      </xsd:complexType>
28    </xsd:element>
29    <xsd:attributeGroup name="ItemDelivery">
30      <xsd:attribute name="partNum" type="SKU" use="required"/>
31      <xsd:attribute name="weightKg" type="xsd:decimal"/>
32      <xsd:attribute name="shipBy">
33        <xsd:simpleType>
34          <xsd:restriction base="xsd:string">
35            <xsd:enumeration value="air"/>
36            <xsd:enumeration value="land"/>
37            <xsd:enumeration value="any"/>
38          </xsd:restriction>
39        </xsd:simpleType>
40      </xsd:attribute>
41    </xsd:attributeGroup>
42  </xsd:schema>