Keep in mind the following when using the Project 3D Canonical Silhouette Edges
command.
You can re-limit the created silhouette edge
using the geometry.
The canonical silhouette command generates one or two marks (edges) if one mark
is made of more that one curves. If those curves do not have the same
geometrical support, the resulting canonical silhouette edges will not be
associative (as for Projection/Intersection commands).
Canonical silhouette edges are associative except in the case of a multiple
distinct marks.
A mark composed of several associated elements is managed as a single
curve (you can constrain it).
If you apply the Parents/Children... command to a sketch
containing a 3D canonical silhouette, the Parents command shows the last
solid feature that modified the canonical silhouette. To see an example of this,
see Parents/Children
section of the More About Projecting 3D Elements onto the Sketch Plane: Parents/Children topic.