This .NET class wraps the AcBrNode ObjectARX class. 

The Node class is the interface class for nodes in a mesh. This class defines the functions that are pertinent to the node level of a mesh, and cannot be directly set by the user.

Autodesk.AutoCAD.BoundaryRepresentation.MeshEntity
    Autodesk.AutoCAD.BoundaryRepresentation.Node

Public sealed Class Node
Inherits MeshEntity

public sealed class Node : MeshEntity;

A node is the intersection or terminating point of two or more edges in a mesh, and thus has associated geometry (for instance, a point). A mapping back to the original brep topology is provided in the form of a backpointer to the dimensionally lowest topology object that contains this node (compare to. MeshEntity.EntityAssociated). If this node is part of a 2D mesh, the associated entity type can be used to classify interior (face) vs. boundary (edge or vertex) nodes. Surface usage data (such as uv parameters and surface normals) must be queried in the context of 2D elements. 

The user generally accesses this class via an element node traverser. The only way to delete the node referenced by this class from the mesh data cache is to delete the mesh object that owns it, or to regenerate the mesh.

Point3d, MeshEntity