public void Write(RawPDU pdu)
{
byte mch = (byte)((_last ? 2 : 0) + (_command ? 1 : 0));
pdu.MarkLength32("PDV-Length");
pdu.Write("Presentation Context ID", _pcid);
pdu.Write("Message Control Header", mch);
pdu.Write("PDV Value", _value);
pdu.WriteLength32();
}