StringBuilder sb = new StringBuilder();
            
            IEnumerable points = new FilteredElementCollector(doc)
                .OfClass(typeof(BasePoint))
                .Cast();
            foreach(BasePoint bp in points)
            {
                string name = bp.IsShared? "surveypoint": "project basepoint";
                BoundingBoxXYZ bb = bp.get_BoundingBox(null);
                XYZ pos = bb.Min;
                sb.AppendLine(string.Format("{0} :  {1}",name, pos));
            }
            TaskDialog.Show("debug",sb.ToString());