This layer is the "Hidden Items" layer. It is called ".BLACK_HOLE" and
these sketched curves you refer to are automatically placed on that
layer when they are used in the definition of a later feature.
So this is very normal behavior.
Paul J. Crane
Business Analyst - Product Design
Computer Aided Engineering Services
Deere & Company
Worldwide Headquarters - EOB 5-9N
One John Deere Place, Moline, IL 61265
