public string ToXML()

MapPoint minPoint = MapPointBuilder.CreateMapPoint(1, 1, 1, 1, 3);
MapPoint maxPoint = MapPointBuilder.CreateMapPoint(5, 5, 5);

// 
//  MapPoint
// 
string xml = minPoint.ToXML();
MapPoint minPointImport = MapPointBuilder.FromXML(xml);
// minPointImport = minPoint

//
// Envelope
//
Envelope envelopeWithID = EnvelopeBuilder.CreateEnvelope(minPoint, maxPoint);

// Envelopes don't have IDs
// envelopeWithID.HasID = false
// envelopeWithID.HasM = true
// envelopeWithID.HasZ = true

xml = envelopeWithID.ToXML();
Envelope envelopeImport = EnvelopeBuilder.FromXML(xml);

//
// Multipoint
//
List<MapPoint> list = new List<MapPoint>();
list.Add(minPoint);
list.Add(maxPoint);

Multipoint multiPoint = MultipointBuilder.CreateMultipoint(list);

xml = multiPoint.ToXML();
Multipoint multipointImport = MultipointBuilder.FromXML(xml);
// multipointImport.PointCount == 2
// multipointImport.HasID = true
// multipointImport.HasM = true
// multipointImport.HasZ= true