public void WriteXml(XmlWriter writer)
{
writer.WriteGuid("id", serial.id);
writer.WritePoint("start", start);
writer.WritePoint("end", end);
writer.WriteColor("col", col);
writer.WriteBool("deleted", isDeleted);
writer.WriteBool("isdrawnbackwards", isdrawnbackwards);
writer.WriteStartElement("points");
foreach (Point thisPoint in midPoints)
writer.WritePoint("point", thisPoint);
writer.WriteEndElement();
}