XML Schema field Element

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Definition and Usage

The field element specifies an XPath expression that specifies the value used to define an identity constraint.

Element Information

  • Parent elements: key, keyref, unique


xpath=XPath expression
any attributes



(The ? sign declares that the element can occur zero or one time inside the field element)

Attribute Description
id Optional. Specifies a unique ID for the element
xpath Required. Identifies a single element or attribute whose content or value is used for the constraint
any attributes Optional. Specifies any other attributes with non-schema namespace

Example 1

The following example shows a field element that specifies the "userID" attribute as the field to use for the identity constraint:

<xs:field xpath="@userID"/>

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