public function GetBoundary($boundary, $charSet, $contentType, $encoding)
{
$result = '';
if ($charSet == '') {
$charSet = $this->CharSet;
}
if ($contentType == '') {
$contentType = $this->ContentType;
}
if ($encoding == '') {
$encoding = $this->Encoding;
}
$result .= $this->TextLine('--' . $boundary);
$result .= sprintf("Content-Type: %s; charset = \"%s\"", $contentType, $charSet);
$result .= $this->LE;
$result .= $this->HeaderLine('Content-Transfer-Encoding', $encoding);
$result .= $this->LE;
return $result;
}