This is the center or corner line up the large open book. It starts at the 5.6 finger crack in the center and heads up the hand to OW crack in the spine of the Book. Great climb to do in the evening on quality rock!
Head over the large round boulder against the "Halfdome" shaped boulder, down to the left to find slings and make 1 rappel into the gully.
Pro to 4" + #3 for belay along with med stoppers.