nil 

A Boolean value that indicates if an element should contain content.

<xsi:nil="boolean">

Values

• true
  The element must be empty and the element declaration in the schema must have an annotation where the nillable attribute is set to true.

• false
  The element cannot be empty. This is the default value.

Example

This example uses an XML Schema, person.xsd, and an instance document, person.xml. The schema contains a type Person that has element declarations for name and height elements. The height element declaration includes a nillable attribute with a value of true. It also contains an element declaration that maps the person element, with its name and height child elements that map to the com:People namespace. The height element includes an xsi:nil attribute with its value set to true to indicate that the element should not contain content.

<xs:schema xmlns:xs= "http://www.w3.org/2001/XMLSchema"
   targetNamespace="urn:contoso-com:People"
   xmlns:ns="urn:contoso-com:People">

   <xs:complexType name="Person">
      <xs:sequence>
         <xs:element name= "name" type="xs:string"/>
         <xs:element name= "height" type="xs:double" nillable="true" />
      </xs:sequence>
   </xs:complexType>

   <xs:element name="Person" type="ns:Person" />
</xs:schema>

<p:person xmlns:p="urn:contoso-com:People">
   <name>John</name>
   <height xmlns:xsi= "http://www.w3.org/2001/XMLSchema-instance"
      xsi:nil="true" />
</p:person>

See Also

Reference

XML Schemas (XSD) Reference
XML Schema Elements
XML Schema Instance Attributes