No problem, just looking to understand

I would like to better understand what was happening when I created this sheet of T1–11 siding to sheath a shed. I put in the first groove and then used move–copy to create the rest. I expected the resulting grooves to be identical to the original one. Although the grooves were copied, faces were created at the top, bottom, and front of the grooves. I had to go in and delete the lines at the top and bottom edges of the grooves so they would appear in the siding. I’m confused about the result of the move–copy operation since if I simply move the groove, it appears exactly as it was created.

T1-11 siding.skp (24.0 KB)

SketchUp always tries to ‘heal’ faces, when you copy ‘voids’, you are actually copying the geometry that define these voids, it won’t cut them from the existing geometry.
Solid operations do, but only on solid objects.

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There has been discussion in the past about the idea of “negative geometry”, that is, something you can copy that erases whatever it lands on. But at this time there is no such thing in SketchUp.

You can only copy existing edges and faces. When you do, they merge with whatever edges and faces existed at the destination. They will cut faces into smaller pieces such as the front, and the top and bottom ends of your grooves. But they won’t erase the faces created by those cuts even though those edges and faces weren’t present in the source groove. Those ‘voids’ are the absence of something rather than something that can be copied.