<types> <schema/> <schema/> question

I am a little bit confused on how to use the <schema> tag in the wsdl's 
<types>

I have seen examples that use 2 schema-tags, one for the RequestMessage 
and one for the ResponseMessage, and I have seen examples, where Request 
and Response element are both a child of the schema-tag. Can some one 
tell me what the correct way of defining my request and response message 
is??

NB: WSDL2Java does not complain about the following, and does not 
complain if I put 2 schema-tags in there. But wsdl.exe insists I define 
it as below.

<wsdl:types>

<xsd:schema
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:tns="http://biryani.med.yale.edu:8081/axis/services/GetXSLIM"
targetNamespace="http://biryani.med.yale.edu:8081/axis/services/GetXSLIM"
 >

<xsd:element name="method2Request">
  <xsd:complexType>
    <xsd:sequence>
        <xsd:element name="cid" type="xsd:string"/>
      </xsd:sequence>
</xsd:complexType>
</xsd:element>

<xsd:element name="method2Response">
  <xsd:complexType>
    <xsd:sequence>
        <xsd:any minOccurs="0"/>
      </xsd:sequence>
</xsd:complexType>
</xsd:element>

</xsd:schema>

</wsdl:types>


OR??


<wsdl:types>

<xsd:schema
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:tns="http://biryani.med.yale.edu:8081/axis/services/GetXSLIM"
targetNamespace="http://biryani.med.yale.edu:8081/axis/services/GetXSLIM"
 >
<xsd:element name="method2Request">
  <xsd:complexType>
    <xsd:sequence>
        <xsd:element name="cid" type="xsd:string"/>
      </xsd:sequence>
</xsd:complexType>
</xsd:element>
</xsd:schema>

<xsd:schema
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:tns="http://biryani.med.yale.edu:8081/axis/services/GetXSLIM"
targetNamespace="http://biryani.med.yale.edu:8081/axis/services/GetXSLIM"
 >
<xsd:element name="method2Response">
  <xsd:complexType>
    <xsd:sequence>
        <xsd:any minOccurs="0"/>
      </xsd:sequence>
</xsd:complexType>
</xsd:element>

</xsd:schema>

</wsdl:types>