private void ConvertTxtInDXF( out byte[] dxfFile) { MemoryStream dxfStream = new MemoryStream(dxfFile); DxfModel model = new DxfModel(DxfVersion.Dxf18); DxfXRecord xr = new DxfXRecord(); model = DxfReader.ReadDxf(dxfStream); foreach (DxfEntity ent in model.Entities) {              if (ent.EntityType.ToString() == 'TEXT') {    string txt = ((DxfText)ent).Text.ToString().Trim();    //put this tag into an XRecord    if (txt.IndexOf('xxTAGxx') > -1) {      //What does the (int) code represent in the DxfXRecord?      //Are they related to the group codes in the DXF Spec?      xr.Values.Add(new DxfXRecordValue(5, txt));      //how do I now add it to the model?      model.____________.Add(xr);      //clear the tag from the dxf      ((DxfText)ent).Text = string.Empty;      break;    }   } } DxfWriter dw = new DxfWriter(dxfStream, model, false); dw.AutoCloseStream = false; dw.Write(true); dxfFile = dxfStream.ToArray(); }