    CHG 9<br>
    PY<br>
    EOS
</strong></p>

<p>This causes surface #9 to take on the value 0.174770E-02 mm as can
be seen by doing an <strong>RTG 9</strong> command. Next, set up the
operands with the following commands:</p>

<p><strong>
    MERIT<br>
    FLCLTH 1ØØ 1 Ø 1Ø<br>
    SA3 Ø 1</br>
    EOS
</strong></p>

<p>The first command causes the program to enter Merit creation
mode. The next command indicates that the paraxial focal length be
targeted to 100 with a weight of 1 for surfaces 0 to 1