Marking heavy timbers with letters or numbers, typically used by boatbuilders and timberframers.
Ever notice that old barn frames were usually marked with Roman rather than Arabic numerals? One reason is that, until you get to C or D - whivch is a hell of a lot of joints - the Roman numerals are all straight lines. Much easier to cut with a chisel or gouge.
The race knife makes the curves easier, using the pivot and the end cutter. The side cutter is good for straight lines.
John Martin