public override void Unmarshal(DataInputStream dis)
        {
            base.Unmarshal(dis);

            if (dis != null)
            {
                try
                {
                    this._emittingEntityID.Unmarshal(dis);
                    this._eventID.Unmarshal(dis);
                    this._stateUpdateIndicator   = dis.ReadUnsignedByte();
                    this._numberOfSystems        = dis.ReadUnsignedByte();
                    this._paddingForEmissionsPdu = dis.ReadUnsignedShort();

                    for (int idx = 0; idx < this.NumberOfSystems; idx++)
                    {
                        ElectronicEmissionSystemData anX = new ElectronicEmissionSystemData();
                        anX.Unmarshal(dis);
                        this._systems.Add(anX);
                    }
                }
                catch (Exception e)
                {
                    if (PduBase.TraceExceptions)
                    {
                        Trace.WriteLine(e);
                        Trace.Flush();
                    }

                    this.RaiseExceptionOccured(e);

                    if (PduBase.ThrowExceptions)
                    {
                        throw e;
                    }
                }
            }
        }