unique key for only nested element

[magister]

Hello,

I want to have a unique Quesiton Id key for each question under
section. Not for every question in the Typed DataSet. Is there
anyway I can do this...?

Thanks, here is my typed Dataset XSD
<?xml version="1.0" encoding="utf-8" ?>
<xs:schema id="TestSection" xmlns=""
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
<xs:element name="TestSection" msdata:IsDataSet="true"
msdata:Locale="en-GB">
<xs:complexType>
<xs:choice maxOccurs="unbounded">
<xs:element name="Section" minOccurs="0" maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element name="Question" minOccurs="0"
maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element name="Option" minOccurs="0"
maxOccurs="unbounded">
<xs:complexType>
<xs:attribute name="Text" type="xs:string" />
<xs:attribute name="Selected" type="xs:string" />
<xs:attribute name="Tooltip" type="xs:string" />
<xs:attribute name="Answer" type="xs:string" />
</xs:complexType>
</xs:element>
</xs:sequence>
<xs:attribute name="Text" type="xs:string" />
<xs:attribute name="Type" type="xs:string" />
<xs:attribute name="Score" type="xs:string" />
<xs:attribute name="Mandatory" type="xs:string" />
<xs:attribute name="Tooltip" type="xs:string" />
<xs:attribute name="MultiSelect" type="xs:string" />
<xs:attribute name="AllowNoSelection" type="xs:string" />
<xs:attribute name="Multiline" type="xs:string" />
<xs:attribute name="MaxLength" type="xs:string" />
<xs:attribute name="MinLength" type="xs:string" />
<xs:attribute name="InitialValue" type="xs:string" />
<xs:attribute name="Validation" type="xs:string" />
<xs:attribute name="Answer" type="xs:string" />
<xs:attribute name="Id" type="xs:short" use="required" />
</xs:complexType>
</xs:element>
</xs:sequence>
<xs:attribute name="Enabled" type="xs:boolean" />
<xs:attribute name="ShowEdit" type="xs:boolean" />
<xs:attribute name="NumberOfQuestions" type="xs:string" />
<xs:attribute name="Type" type="xs:string" />
<xs:attribute name="Score" type="xs:string" />
<xs:attribute name="Text" type="xs:string" />
<xs:attribute name="Id" type="xs:short" use="required" />
</xs:complexType>
</xs:element>
</xs:choice>
</xs:complexType>
<xs:key name="TestSectionKey1" msdata:PrimaryKey="true">
<xs:selector xpath=".//Section" />
<xs:field xpath="@Id" />
</xs:key>
<xs:key name="QuestionKey" msdata:PrimaryKey="true">
<xs:selector xpath=".//Question" />
<xs:field xpath="@Id" />
</xs:key>
</xs:element>
</xs:schema>