These two will point downward, as we see in this diagram. They go into the board or into the page, and these four groups are coming out of the board, as shown here. They're going to come out of the page. So horizontal lines are drawn in front of the plane coming out of the board, while vertical lines are drawn in the back of the plane going into the board. So a fissure projection is nothing more than a way to basically describe the three dimensional stereo chemistry of the sugar molecule. Now, the final thing I'd like to discuss are diary, isomers and ephemeris.