How to create xml based on this xsd?

Question

I have this XSD and I am trying to create the XML file using NATIVEXML (Delphi).

<xs:element maxOccurs="unbounded" name="Program">
 <xs:complexType>
  <xs:attribute name="Provider" use="required">
   <xs:simpleType>
    <xs:restriction base="xs:string">
     <xs:minLength value="2" />
     <xs:maxLength value="6" />
    </xs:restriction>
   </xs:simpleType>
  </xs:attribute>
  <xs:more attributes\>
 </xs:complexType>
</xs:element>

I created the following code:

node := Adoc.Root.NodeNew('Student');
node.WriteAttributeInteger('Provider',var_with_data);

how can I create the restrictions?