I was fiddling about and discovered that it's possible to delete everything from a 3D sketch, without SolidWorks then automatically deleting that sketch. I have attached an example file which contains no entities in it whatsoever, yet it does contain four empty 3D sketches.

Is there any reason why SolidWorks would allow a 3D sketch to be empty but not a 2D one?

Just curious.

[ file saved with Student 2020 version ]