Question

I have a schema like below, the color elements of default and instance have identical restriction (red/green/blue). I want to move the restriction to higher level and set all color element with it (Like declare a type or enum in Java/C#)

How can I do for that?

<xs:element name="something">
    <xs:complexType>
        <xs:sequence>
            <xs:element name="instance" maxOccurs="unbounded">
                <xs:complexType>
                    <xs:attribute name="name" type="xs:string" use="required"/>
                    <xs:attribute name="color" use="required">
                        <xs:simpleType>
                            <xs:restriction base="xs:string">
                                <xs:enumeration value="red"/>
                                <xs:enumeration value="green"/>
                                <xs:enumeration value="blue"/>
                            </xs:restriction>
                        </xs:simpleType>
                    </xs:attribute>
                </xs:complexType>
            </xs:element>
            <xs:element name="default">
                <xs:complexType>
                    <xs:attribute name="color" use="required">
                        <xs:simpleType>
                            <xs:restriction base="xs:string">
                                <xs:enumeration value="red"/>
                                <xs:enumeration value="green"/>
                                <xs:enumeration value="blue"/>
                            </xs:restriction>
                        </xs:simpleType>
                    </xs:attribute>
                </xs:complexType>
            </xs:element>
        </xs:sequence>
    </xs:complexType>
</xs:element>

Answer 1

Define the type:

<xs:simpleType name="colorenum">
    <xs:restriction base="xs:string">
        <xs:enumeration value="red"/>
        <xs:enumeration value="green"/>
        <xs:enumeration value="blue"/>
    </xs:restriction>
</xs:simpleType>

And reference it:

<xs:attribute name="color" type="colorenum" />