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XML Schema field Element

Definition and Usage

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

<field
id=ID
xpath=XPath expression
any attributes
>

(annotation?)

</field>

(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

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"/>