CRM_Utils_System::setHttpHeader('Content-Length', strlen($calendar));
CRM_Utils_System::setHttpHeader("Content-Disposition", "$disposition; filename=\"$fileName\"");
CRM_Utils_System::setHttpHeader("Pragma", "no-cache");
CRM_Utils_System::setHttpHeader('Content-Length', strlen($calendar));
CRM_Utils_System::setHttpHeader("Content-Disposition", "$disposition; filename=\"$fileName\"");
CRM_Utils_System::setHttpHeader("Pragma", "no-cache");