letter        = unicode_letter | "_" .
decimal_digit = "0" … "9" .
binary_digit  = "0" | "1" .
octal_digit   = "0" … "7" .
hex_digit     = "0" … "9" | "A" … "F" | "a" … "f" .
</pre>

<h2 id="Lexical_elements">Lexical elements</h2>

<h3 id="Comments">Comments</h3>

<p>
Comments serve as program documentation. There are two forms:
</p>

<ol>
<li>