In the world of metal we call them "witness marks", same principle.
And don't worry I'm not wanting to get into a long drawn out debate over the correct term for what is effectively a smudge.
If engineers/machinists/fitters need to produce a perfectly flat surface . "Engineers Blue" would be applied to a surface plate. The job would then be placed face down onto the surface plate , gently rubbed back and forth and then removed . Thus delineating the high spots. Also used for checking gear meshing etc..
Anyway it's basically the same thing.
I wonder if the genuine "witness marks/ Planar leveling marks" could not have been made simply by accident.
The marks were painted in water based red ochre , which would have dried to a chalky texture. If the whole block were then accidently abraded or rubbed the pigment would have been smudged onto the adjacent peaks.
The "Corner Glyph" witness marks seem to be quite unlike the "contentous glyph" witness marks.
Post Edited (11-Sep-14 23:56)