Specifies an XML Path Language (XPath) expression that selects a set of elements for an identity constraint (unique, key, and keyref elements).
<selector id = ID xpath = a subset of XPath expression {any attributes with non-schema Namespace}…> Content: (annotation?) </selector>
Optional.
Required.
Number of occurrences | One time |
Parent elements | key, keyref, unique |
Contents | annotation |
Selector ::= Path ( '|' Path )* Path ::= ('.//')? Step ( '/' Step )* Step ::= '.' | NameTest NameTest ::= QName | '*' | NCName ':' '*'
Note When using XPath, you must use fully qualified names. For example,myNS:localName
instead oflocalName
.
The following fragment is a selector element that selects all expense elements with a field element that selects an approved attribute.
<selector xpath=".//expense"/> <field xpath="@approved"/>
XML Schema Reference (XSD) | XML Schema Elements
For more information, see the W3C XML Schema Part 1: Structures Recommendation at http://www.w3.org/TR/2001/REC-xmlschema-1-20010502/#element-selector.