xs:keyref

Purpose

Defines an identity constraint of type xs:keyref. This provides for constraints that are similar to referential integrity. The scope of the constraint is a single XML document.

Each tuple value of an xs:refkey identity constraint must match the corresponding value of the identity constraint of type xs:key or xs:unique that is referenced by the refer attribute.

For details of the construction of the tuples representing the values of an identity constraint, please see section 3.11.4 Identity-constraint Definition Validation Rules of the W3C documentation XML Schema Part 1: Structures.

Parent element xs:element
Child elements xs:annotation, xs:field, xs:selector
Attributes id, name, refer
Attributes
Name Type Description
id xs:ID Assigns an identifier to the schema node.
name xs:NCName

The names of all identity constraints (xs:key, xs:keyref and xs:unique) must be unique within a schema document.

refer xs:QName The QName of a referenced identity constraint of type xs:key or xs:unique.