Structures are encoded as a xs:complexTypewith all of the fields appearing in a sequence. All fields are encoded as an xs:element. All elements have minOccurs set 0 to allow for compact XML representations. If an element is missing the default value for the field type is used. If the field type is a structure the default value is an instance of the structure with default values for each contained field.

Types which have a NULL value defined shall have the nillable="true" flag set.

For example, the Read service has a ReadValueIdstructure in the request. The XML schema would look like:

<xs:complexType name="ReadValueId">

<xs:sequence>

<xs:element name="NodeId" type="tns:NodeId"

minOccurs="0" nillable="true" />

<xs:element name="AttributeId" type="xs:int" minOccurs="0" />

<xs:element name="IndexRange" type="xs:string"

minOccurs="0" nillable="true" />

<xs:element name="DataEncoding" type="tns:NodeId"

minOccurs="0" nillable="true" />

</xs:sequence>

</xs:complexType>