A new labeling theory and method are proposed for the two-dimensional line drawing with hidden-part-draw of a three-dimensional
manifold curved surface object with trihedral vertices. Some rules for labeling line drawing with
hidden-part-draw are established. There are 69 kinds of junctions for line drawing with hidden-part-draw, including 8 kinds of
Y-junctions, 16 kinds of W-junctions, 11 kinds of S-junctions and 34 kinds of V-junctions. Our labeling theory and
method can discriminate between correct and incorrect line drawings with hidden-part-draw for manifold curved surface
object, and handle line drawings with hidden-part-draw for complicated objects that consist of manifold planar and
curved surface ones.