XML Schema extension element

XSD Element

Definition and usage

The extension element extends the elements of simpleType or complexType.

Element information

Occurrence times One
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 the unique ID of 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 declaration is within the extension element, which can appear zero or once, and the * symbol indicates that the element can appear zero or more times.)

Instance

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>

XSD Element