XML Schema keyref Element

Definition and Usage

The keyref element specifies that an attribute or element value correspond to those of the specified key or unique element.

The keyref element MUST contain the following (in order):

one and only one selector element (contains an XPath expression that specifies the set of elements across which the values specified by field must be unique)
one or more field elements (contains an XPath expression that specifies the values that must be unique for the set of elements specified by the selector element)

Element Information

Parent elements: element

Syntax

<keyref
id=ID
name=NCName
refer=QName
any attributes
>

(annotation?,(selector,field+))

</keyref>

(The ? sign declares that the element can occur zero or one time, and the + sign declares that the element must occur one or more times inside the keyref element)

Attribute	Description
id	Optional. Specifies a unique ID for the element
name	Required. Specifies the name of the keyref element
refer	Required. Specifies the name of a key or unique element defined in this or another schema
any attributes	Optional. Specifies any other attributes with non-schema namespace

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