SoapHeader is a special low-level class for passing or returning SOAP headers. It is just a data holder and it does not have any special methods except a constructor. It can be used in the SoapClient::__call() method to pass a SOAP header or in a SOAP header handler to return the header in a SOAP response. namespace and name are namespace and name of the SOAP header element. data is a SOAP header's content. It can be a PHP value or SoapVar object. mustUnderstand and actor are values for mustUnderstand and actor attributes of this SOAP Header element.
See also SoapClient::__call(), SoapParam::SoapParam(), and SoapVar::SoapVar().