XML Schema extension element
Definition and usage
The extension element extends the elements of simpleType or complexType.
Element information
| Occurrence | Once |
| Parent element | complexContent |
| Content | annotation, attribute, attributeGroup, anyAttribute, choice, all, sequence, group |
Syntax
<extension id=ID base=QName any attributes > (annotation?,((group|all|choice|sequence)?, ((attribute|attributeGroup)*,anyAttribute?))) </extension>
| Attribute | Description |
|---|---|
| id | Optional. Specifies a unique ID for the element. |
| base | Required. Specifies the name of the built-in data type, simpleType, or complexType element. |
| xml:lang | Optional. Specifies the language used in the content. |
(The ? symbol is declared within the extension element, which can appear zero or one times, and the * symbol declares that the element can appear zero or more times.)
Instance
Example 1
The following example extends an existing simpleType element by adding an attribute:
<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:simpleType name="size">
<xs:restriction base="xs:string">
<xs:enumeration value="small" />
<xs:enumeration value="medium" />
<xs:enumeration value="large" />
</xs:restriction>
</xs:simpleType>
<xs:complexType name="jeans">
<xs:simpleContent>
<xs:extension base="size">
<xs:attribute name="sex">
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:enumeration value="male" />
<xs:enumeration value="female" />
</xs:restriction>
</xs:simpleType>
</xs:attribute>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
</xs:schema>
Example 2
The following example extends an existing complexType element by adding three elements:
<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="employee" type="fullpersoninfo"/>
<xs:complexType name="personinfo">
<xs:sequence>
<xs:element name="firstname" type="xs:string"/>
<xs:element name="lastname" type="xs:string"/>
</xs:sequence>
</xs:complexType>
<xs:complexType name="fullpersoninfo">
<xs:complexContent>
<xs:extension base="personinfo">
<xs:sequence>
<xs:element name="address" type="xs:string"/>
<xs:element name="city" type="xs:string"/>
<xs:element name="country" type="xs:string"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
</xs:schema>
