HOME

Schema Tutorial
XSD HOME
XSD Intro
XSD Why Use
XSD How To
XSD <schema>

Simple Types
XSD Elements
XSD Attributes
XSD Restrictions

Complex Types
XSD Elements
XSD Empty
XSD Elements Only
XSD Text Only
XSD Mixed
XSD Indicators
XSD <any>
XSD <anyAttribute>
XSD Substitution
XSD Example

Data Types
XSD String
XSD Date
XSD Numeric
XSD Misc

XSD Summary

References
XSD Reference
XSD Validator

Selected Reading
Web Statistics
Web Glossary
Web Hosting
Web Quality

W3Schools Forum

Helping W3Schools

XML Schema union Element

Complete XML Schema Reference

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

Get Your Diploma!

W3Schools' Online Certification Program is the perfect solution for busy professionals who need to balance work, family, and career building.

The HTML Certificate is for developers who want to document their knowledge of HTML, XHTML, and CSS.

The ASP Certificate is for developers who want to document their knowledge of ASP, SQL, and ADO.

Jump to: Top of Page or HOME or Printer friendly page

W3Schools provides material for training only. We do not warrant the correctness of its contents. The risk from using it lies entirely with the user. While using this site, you agree to have read and accepted our terms of use and privacy policy.

W3Schools was converted to XHTML in December 1999