The document element is called [wsdl:]definitions in the http://schemas.xmlsoap.org/wsdl/ namespace.

We'll use the 'name' attribute to give a common name for the tideinfo service:

<wsdl:definitions name="tideinfo"
   xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/"
   targetNamespace="http://www.smallx.com/services/tideinfo/2005/wsdl"
   xmlns:service="http://www.smallx.com/services/tideinfo/2005/wsdl"
>
   <wsdl:documentation xmlns="http://www.w3.org/1999/xhtml">
   <p>This service provides tide information by NOAA tide monitor location.</p>
   </wsdl:documentation>
</wsdl:definitions>

Inside this element is where all the descriptions of the messages/etc. go.

The [wsdl:]documentation element is nice to use for descriptions of how to use the service or where to get more information.