from The Century Dictionary.
- noun A mark put upon a set of warp-threads before they are placed on the warp-beam of a loom, to mark off a certain definite length. The mark shows in the woven fabric, and serves as a measure for cutting.
Sorry, no etymologies found.
In order to achieve the correct length, yet also cut the board so that the tongue fit in the groove, the board first had to be flipped over and the cut-mark drawn.
Dr. Hamdallah Bearat from the Ira A. Fulton Schools of Engineering at Arizona State University determined that one cut-mark even contained a tiny, embedded piece of rock that was likely left behind during the butchering process.