XML Schema unionElement

XML Schema 参考手册Complete XML Schema Reference Manual

Definition and Usage

The union element defines a collection of multiple simpleType definitions.

Element Information

  • Parent element: simpleType

Syntax

<union
id=ID
memberTypes="list of QNames"
any attributes
>

(annotation?,(simpleType*))

</union>

(The ? sign declares that the element can appear zero or one time within the union element.)

Attributes Description
id Optional. Specifies a unique ID for the element.
memberTypes Optional. Specifies a list of names of built-in data types or simpleType elements defined in the schema.
any attributes Optional. Specifies any other attributes with a non-schema namespace.

Example 1

This example is a simple type that combines 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>

XML Schema 参考手册Complete XML Schema Reference Manual Other Extensions