Thanks, Yuri!
I believe the difference is the raised edge around ends of the link:
but it may also refer to the pair of ribs in the center.
Raised knock out/pusher marks on flat surfaces are not usually a concern for me. I glued a 3mm diameter disk of sandpaper onto the end face of a 3mm hardwood dowel and mount it into my electric rotary tool. Removing the marks while the tracks are still on the sprues is quick and easy.
Sunken marks are filled with punched disks of styrene sheet and treated as if they are raised. I never have to use a putty or filler.
Thanks again,
KL