trong></p>

<p>This form of the command just lists the paraxial ray data at
surface 3. With <strong>HEADINGS OFF</strong>, no heading would appear
in single surface output. There are also paraxial output commands
which display paraxial incidence angle tangents rather than slope
tangents. Try them.</p>

<p>The 3<sup>rd</sup>, 5<sup>th</sup> and 7<sup>th</sup> order
aberration values calculated are based on the work of Buchdahl
[H. A. Buchdahl, <em>Optical Aberration Coefficients</em>, Dover
1968]. To calcula