<p>%%index text="background color or symbol"%%Use
the &quot;Extras&#8594;Options&quot; menu item to set options:
</p>
<ul>
<li><b>Background colour for scale factor</b><br>
Show evaluation using a colored background. Without this option
the evaluation is shown by symbols in the fourth table column.
<ul>
<li>++<br>
Very good, scale factor is a power of 2.
</li>
<li>+<br>
Good, scale factor is integer.
</li>
<li><i>no symbol</i><br>
Acceptable, scale factor is a rational number.
</li>
</ul>
</li>
</ul>
<p>The option is used for all following calculations.<br>&nbsp;<br>
</p>
%%img src=sc-main2.png alt="no background colour used"%%
