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XML Schema extension Element

Definition and Usage

The extension element extends an existing simpleType or complexType element.

Element Information

Parent elements: simpleContent, complexContent

Syntax

<extension
id=ID
base=QName
any attributes
>

(annotation?,((group|all|choice|sequence)?,
((attribute|attributeGroup)*,anyAttribute?)))

</extension>

(The ? sign declares that the element can occur zero or one time, and the * sign declares that the element can occur zero or more times inside the extension element)

Attribute	Description
id	Optional. Specifies a unique ID for the element
base	Required. Specifies the name of a built-in data type, a simpleType element, or a complexType element
any attributes	Optional. Specifies any other attributes with non-schema namespace

Example 1

The following example extends an existing simpleType 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>

Complete XML Schema Reference