A sample WSDL document

<definitions xmlns="http://schemas.xmlsoap.org/wsdl/" 
  xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/" 
  xmlns:http="http://schemas.xmlsoap.org/wsdl/http/" 
  xmlns:xs="http://www.w3.org/2001/XMLSchema" 
  xmlns:soapenc="http://schemas.xmlsoap.org/soap/encoding/" 
  xmlns:mime="http://schemas.xmlsoap.org/wsdl/mime/" 
  xmlns:y="http://example.org/math/" 
  xmlns:ns="http://example.org/math/types/" 
  targetNamespace="http://example.org/math/">
   <types>
     <xs:schema targetNamespace="http://example.org/math/types/" 
       xmlns="http://example.org/math/types/" 
       elementFormDefault="unqualified" attributeFormDefault="unqualified">
         <xs:complexType name="MathInput">
            <xs:sequence>
               <xs:element name="x" type="xs:double"/>
               <xs:element name="y" type="xs:double"/>
            </xs:sequence>
         </xs:complexType>
         <xs:complexType name="MathOutput">
            <xs:sequence>
               <xs:element name="result" type="xs:double"/>
            </xs:sequence>
         </xs:complexType>
         <xs:element name="Add" type="MathInput"/>
         <xs:element name="AddResponse" type="MathOutput"/>
         <xs:element name="Subtract" type="MathInput"/>
         <xs:element name="SubtractResponse" type="MathOutput"/>
         <xs:element name="Multiply" type="MathInput"/>
         <xs:element name="MultiplyResponse" type="MathOutput"/>
         <xs:element name="Divide" type="MathInput"/>
         <xs:element name="DivideResponse" type="MathOutput"/>
      </xs:schema>
   </types>
   <message name="AddMessage">
      <part name="parameters" element="ns:Add"/>
   </message>
   <message name="AddResponseMessage">
      <part name="parameters" element="ns:AddResponse"/>
   </message>
   <message name="SubtractMessage">
      <part name="parameters" element="ns:Subtract"/>
   </message>
   <message name="SubtractResponseMessage">
      <part name="parameters" element="ns:SubtractResponse"/>
   </message>
   <message name="MultiplyMessage">
      <part name="parameters" element="ns:Multiply"/>
   </message>
   <message name="MultiplyResponseMessage">
      <part name="parameters" element="ns:MultiplyResponse"/>
   </message>
   <message name="DivideMessage">
      <part name="parameters" element="ns:Divide"/>
   </message>
   <message name="DivideResponseMessage">
      <part name="parameters" element="ns:DivideResponse"/>
   </message>
   <portType name="MathInterface">
      <operation name="Add">
         <input message="y:AddMessage"/>
         <output message="y:AddResponseMessage"/>
      </operation>
      <operation name="Subtract">
         <input message="y:SubtractMessage"/>
         <output message="y:SubtractResponseMessage"/>
      </operation>
      <operation name="Multiply">
         <input message="y:MultiplyMessage"/>
         <output message="y:MultiplyResponseMessage"/>
      </operation>
      <operation name="Divide">
         <input message="y:DivideMessage"/>
         <output message="y:DivideResponseMessage"/>
      </operation>
   </portType>
   <binding name="MathSoapHttpBinding" type="y:MathInterface">
      <soap:binding style="document" 
         transport="http://schemas.xmlsoap.org/soap/http"/>
      <operation name="Add">
         <soap:operation soapAction="http://example.org/math/#Add"/>
         <input>
            <soap:body use="literal"/>
         </input>
         <output>
            <soap:body use="literal"/>
         </output>
      </operation>
      <operation name="Subtract">
         <soap:operation soapAction="http://example.org/math/#Subtract"/>
         <input>
            <soap:body use="literal"/>
         </input>
         <output>
            <soap:body use="literal"/>
         </output>
      </operation>
      <operation name="Multiply">
         <soap:operation soapAction="http://example.org/math/#Multiply"/>
         <input>
            <soap:body use="literal"/>
         </input>
         <output>
            <soap:body use="literal"/>
         </output>
      </operation>
      <operation name="Divide">
         <soap:operation soapAction="http://example.org/math/#Divide"/>
         <input>
            <soap:body use="literal"/>
         </input>
         <output>
            <soap:body use="literal"/>
         </output>
      </operation>
   </binding>
   <service name="MathService">
      <port name="MathEndpoint" binding="y:MathSoapHttpBinding">
         <soap:address location="http://localhost/math/math.asmx"/>
      </port>
   </service>
</definitions>

Reference: Understanding WSDL at MSDN Library