The three files PCCOLOR.OPT, PCCOLOR.RAY, and GLASS.MED contain the information you need to reproduce the experiment on chromatic aberration of a planoconvex lens. Load each of these files and run Layout. The red ray corresponds to red light, the blue ray to blue light, and the yellow ray to yellow light, each of a specific wavelength as indicated in the ray table. Notice how the color to be used on the screen is selected with a letter in a column separator of the ray table.
From the Layout menu, select Posn and put the arrow on the
focus. Then select Magn and use 
to get a close look at
the rays converging to the focal plane. The blue ray is inside, converged
more than the red ray because the index of refraction for blue light is
higher than for red light.
From the Main menu, select Plot and you will see the rays as they cross the focal plane. You may modify the ray table so that it only includes one color. Do this by deleting the lines you do not want. (Use the delete key; reload the table to start over.) Notice that at the upper left there is a line that says ``7 rays''. If you delete rays, you must also change this line so that it has the right number of rays.
With rays deleted, from the Main menu, select Auto and then Plot and you will see that the screen has been moved to a point of best focus for whatever rays remain. You can inspect the optics table to see just where this is, and by noting the positions of the screen for each color, you can record the lateral chromatic aberration of the lens.