About Manifold Representations of Faceted Geometry
You can create manifold models of the faceted surfaces in Facet Modeling. You can work with both open and closed manifold models.
Manifold representations of a model have all the triangles connected continuously by their edges except for boundary edges.
Closed-manifold objects bound volume, whereas open-manifold objects do not.
If a point set represents a closed object, the > 
Wrap command creates a closed object. However, noise in the scan data can result in a wrap model that is not closed or contains nonmanifold edges, that is, some triangles in the model are not connected continuously by their edges.
Wrap command creates a closed object. However, noise in the scan data can result in a wrap model that is not closed or contains nonmanifold edges, that is, some triangles in the model are not connected continuously by their edges.