XML Schema union Element
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Definition and Usage
The union element defines a simple type as a collection (union) of values from specified simple data types.
Element Information
- Parent elements: simpleType
 
Syntax
<union
id=ID
memberTypes="list of QNames"
any attributes
>
(annotation?,(simpleType*))
</union>
(The ? sign declares that the element can occur zero or one time inside the union element)
| Attribute | Description | 
|---|---|
| id | Optional. Specifies a unique ID for the element | 
| memberTypes | Optional. Specifies a list of built-in data types or simpleType elements defined in a schema | 
| any attributes | Optional. Specifies any other attributes with non-schema namespace | 
Example 1
This example shows a simple type that is a union of two simple types:
<xs:element name="jeans_size">
  <xs:simpleType>
    <xs:union memberTypes="sizebyno sizebystring" />
  </xs:simpleType>
</xs:element>
<xs:simpleType name="sizebyno">
  <xs:restriction base="xs:positiveInteger">
    <xs:maxInclusive value="42"/>
  </xs:restriction>
</xs:simpleType>
<xs:simpleType name="sizebystring">
  <xs:restriction base="xs:string">
    <xs:enumeration value="small"/>
    <xs:enumeration value="medium"/>
    <xs:enumeration value="large"/>
  </xs:restriction>
</xs:simpleType>
❮ Complete XML Schema Reference

