xml – Xsd和继承

我有一个像这样的xsd

<xsd:complexType name="A">  
        <xsd:complexContent>  
            <xsd:sequence>  
                <xsd:element name="options">  
                    <xsd:complexType>  
                        <xsd:sequence>  
                            <xsd:element name="Day">  
                            ...  
                            </xsd:element>  
                        </xsd:sequence>  
                    </xsd:complexType>  
                </xsd:element>  
            </xsd:sequence>  
        </xsd:complexContent>  
</xsd:complexType>  

<xsd:complexType name="B">  
    <xsd:complexContent>
        <xsd:extension base="A">
        ...What would go here...
        </xsd:extension>
    </xsd:complexContent>
</xsd:complexType>

所以基本上我想要A类有一个选项序列(例如Day，Week)，然后我希望B继承A，并拥有所有的A选项和额外的2或3选项，如小时，秒。

这里是我想出的模式：

<?xml version="1.0" encoding="utf-8"?>
<schema id="inheritance"
    targetNamespace="http://test.com"
    elementFormDefault="qualified"
    xmlns="http://www.w3.org/2001/XMLSchema"
    xmlns:test="http://test.com"
>
    <element name="Time">
        <complexType>
            <sequence>
                <element name="First" type="test:A" />
                <element name="Second" type="test:B" />
            </sequence>
        </complexType>
    </element>

    <complexType name="shortOptions">
        <sequence>
            <element name="Day" />
        </sequence>
    </complexType>

    <complexType name="longOptions">
        <complexContent>
            <extension base="test:shortOptions">
                <sequence>
                    <element name="Week" />
                </sequence>
            </extension>
        </complexContent>
    </complexType>

    <complexType name="A">
        <sequence>
            <element name="options" type="test:shortOptions" />
        </sequence>
    </complexType>

    <complexType name="B">
        <sequence>
            <element name="options" type="test:longOptions" />
        </sequence>
    </complexType>

</schema>

其中似乎适合这个xml：

<?xml version="1.0" encoding="utf-8" ?>
<Time xmlns="http://test.com">
    <First>
        <options>
            <Day>Today</Day>
        </options>
    </First>
    <Second>
        <options>
            <Day>Tomorrow</Day>
            <Week>This Week</Week>
        </options>
    </Second>
</Time>