private static string WriteGpsData(XmlWriter writer, GpsSource gpsSource)
{
if (gpsSource == null)
return null;
if (_SourceMapping.ContainsKey(gpsSource.SourceType))
writer.WriteXmlAttribute("I", _SourceMapping[gpsSource.SourceType]);
writer.WriteXmlAttribute("J", GetAccuracy(gpsSource.HorizontalAccuracy));
writer.WriteXmlAttribute("K", GetAccuracy(gpsSource.VerticalAccuracy));
return null;
}