title: Details on WSDL Types
body: <p>I am learning WSDL by going through the <a href="http://www.w3.org/TR/wsdl" rel="nofollow">online documentation</a> and came across below statement:</p>
  
  <blockquote>
    <p>The types element encloses data type definitions that are relevant for
    the exchanged messages. For maximum interoperability and platform
    neutrality, WSDL prefers the use of XSD as the canonical type system,
    and treats it as the intrinsic type system.</p>
  </blockquote>
  
  <p>I am new to WSDL and finding difficulty in understanding this. what does it mean <code>WSDL prefers the use of XSD as the canonical type system, and treats it as the intrinsic type system.</code>?</p>
  
  <p>Also it sys:</p>
  
  <blockquote>
    <p>The XSD type system can be used to define the types in a message
    regardless of whether or not the resulting wire format is actually
    XML, or whether the resulting XSD schema validates the particular wire
    format. This is especially interesting if there will be multiple
    bindings for the same message, or if there is only one binding but
    that binding type does not already have a type system in widespread
    use. In these cases, the recommended approach for encoding abstract types using XSD.</p>
  </blockquote>
  
  <p>What it means <code>This is especially interesting if there will be multiple bindings for the same message, or if there is only one binding but that binding type does not already have a type system in widespread use.</code>?</p>
  
  <p>Also what it means about <code>encoding abstract types using XSD</code>?</p>