de>** – A real constant for e (<code>2.7182818284590451</code>). <br  />
 Useful for trigonometric or geometric calculations.</li>
</ul>
<h3><a class="anchor" id="autotoc_md574"></a>
TRUE and FALSE</h3>
<p>In Retro Rocket BASIC, <code>TRUE</code> is defined as <code>1</code> and <code>FALSE</code> as <code>0</code>. This differs from BBC BASIC, where <code>TRUE</code> was <code>-1</code>.</p>
<p><b>Why BBC BASIC used <code>-1</code>:</b> <br  />
 BBC BASIC, like many early BASIC dialects, used 16-bit sign