public XmlDocument ToXML()

public static OrderLineFieldValueCollection CopyCollection(OrderLineFieldValueCollection col)
{
    XmlDocument xmlDoc = col.ToXML();
    OrderLineFieldValueCollection newCol = new OrderLineFieldValueCollection();
    XmlNode root = xmlDoc["OrderLineFieldValueCollection"];
    foreach (XmlNode fieldValueNode in root.SelectNodes("OrderLineFieldValue")
    {
        String systemName = fieldValueNode["OrderLineFieldSystemName"].InnerText();
        String value = fieldValueNode["Value"].InnerText();
        newCol.Add(new OrderLineFieldValue(systemName, value));
    }
 
    return newCol;
}