我知道schema可以使xml语言有一定含义，可如何使用schema呢？
最好能举个例子！
參考答案:你可以利用名称空间，首先建立一个XSD文件，然后在XML文件中引用,以下示例说明一个订单架构的实例文档 po.xml，由前一个示例中的 po.xsd 进行验证。
po.xsd:
<xs:schema xmlns:xs=""
xmlns="" elementFormDefault="qualified">
<xs:annotation>
<xs:documentation xml:lang="en">
Purchase order schema for Example.com.
Copyright 2000 Example.com. All rights reserved.
</xs:documentation>
</xs:annotation>
<xs:element name="purchaseOrder" type="PurchaseOrderType"/>
<xs:element name="comment" type="xs:string"/>
<xs:complexType name="PurchaseOrderType">
<xs:sequence>
<xs:element name="shipTo" type="USAddress"/>
<xs:element name="billTo" type="USAddress"/>
<xs:element ref="comment" minOccurs="0"/>
<xs:element name="items" type="Items"/>
</xs:sequence>
<xs:attribute name="orderDate" type="xs:date"/>
</xs:complexType>
<xs:complexType name="USAddress">
<xs:sequence>
<xs:element name="name" type="xs:string"/>
<xs:element name="street" type="xs:string"/>
<xs:element name="city" type="xs:string"/>
<xs:element name="state" type="xs:string"/>
<xs:element name="zip" type="xs:decimal"/>
</xs:sequence>
<xs:attribute name="country" type="xs:NMTOKEN"
fixed="US"/>
</xs:complexType>
<xs:complexType name="Items">
<xs:sequence>
<xs:element name="item" minOccurs="0" maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element name="productName" type="xs:string"/>
<xs:element name="quantity">
<xs:simpleType>
<xs:restriction base="xs:positiveInteger">
<xs:maxExclusive value="100"/>
</xs:restriction>
</xs:simpleType>
</xs:element>
<xs:element name="USPrice" type="xs:decimal"/>
<xs:element ref="comment" minOccurs="0"/>
<xs:element name="shipDate" type="xs:date" minOccurs="0"/>
</xs:sequence>
<xs:attribute name="partNum" type="SKU" use="required"/>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
<!-- Stock Keeping Unit, a code for identifying products >
<xs:simpleType name="SKU">
<xs:restriction base="xs:string">
<xs:pattern value="\d{3}-[A-Z]{2}"/>
</xs:restriction>
</xs:simpleType>
</xs:schema>
po.xml:
<?xml version="1.0"?>
<purchaseOrder xmlns="" orderDate="1999-10-20">
<shipTo country="US">
<name>Alice Smith</name>
<street>123 Maple Street</street>
<city>Mill Valley</city>
<state>CA</state>
<zip>90952</zip>
</shipTo>
<billTo country="US">
<name>Robert Smith</name>
<street>8 Oak Avenue</street>
<city>Old Town</city>
<state>PA</state>
<zip>95819</zip>
</billTo>
<comment>Hurry, my lawn is going wild!</comment>
<items>
<item partNum="872-AA">
<productName>Lawnmower</productName>
<quantity>1</quantity>
<USPrice>148.95</USPrice>
<comment>Confirm this is electric</comment>
</item>
<item partNum="926-AA">
<productName>Baby Monitor</productName>
<quantity>1</quantity>
<USPrice>39.98</USPrice>
<shipDate>1999-05-21</shipDate>
</item>
</items>
</purchaseOrder>
哎，粘的太多了～！
