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


memberTypes="list of QNames"
any attributes



(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:union memberTypes="sizebyno sizebystring" />

<xs:simpleType name="sizebyno">
  <xs:restriction base="xs:positiveInteger">
    <xs:maxInclusive value="42"/>

<xs:simpleType name="sizebystring">
  <xs:restriction base="xs:string">
    <xs:enumeration value="small"/>
    <xs:enumeration value="medium"/>
    <xs:enumeration value="large"/>

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