internal static void WriteXml(XmlWriter writer, ObjectRef objectRef)
        {
            if (objectRef.GetType() != typeof(ObjectRef))
            {
                string xsiPrefix = RmXmlSerializer.UseXsiPrefix(writer);
                string oePrefix  = RmXmlSerializer.UseOpenEhrPrefix(writer);

                string typeName = ((IRmType)objectRef).GetRmTypeName();
                if (!string.IsNullOrEmpty(oePrefix))
                {
                    typeName = oePrefix + ":" + typeName;
                }

                writer.WriteAttributeString(xsiPrefix, "type", XsiNamespace, typeName);
            }

            ((System.Xml.Serialization.IXmlSerializable)objectRef).WriteXml(writer);
        }