The basic unit of a SOAP payload is the SOAP Envelope. The envelope can contain a body, a header and attachments. But the most common usage just has a body.

<?xml version="1.0" encoding="UTF-8"?>
<soapenv:Envelope 
    soapenv:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" 
    xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" 
    xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/">
  <soapenv:Body>
  < STUFF GOES HERE >
  </soapenv:Body>
</soapenv:Envelope>

There may also be a <soapenv:Header /> element inside the envelope, separate from the Body but this is only if metadata is needed to handle the Body element's contents correctly.