A mark or stake set to indicate the position (approximate or exact) of a property corner, instrument station, or other survey point. A witness may be a rock, tree, or other object; e.g., a blazed tree on the bank of a river to indicate a corner at the intersection of some survey line with the center line of the stream, which, therefore, cannot be marked directly; a stake driven so as to stand out; and a stake marked with a station number, driven flush with or below the surface of the ground.