Being boolean you just need to use the value of 1 for bStart.<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:urn="urn:nms:delivery">  <soapenv:Header/>  <soapenv:Body>      <urn:PrepareProof>        <urn:sessiontoken>___faked785-5bad-48f9-824d-e637fa869321</urn:sess...