 </blockquote>

        <pre><code>i = 0         # a counter for a loop
x, y = 0, 0   # x and y coordinates
p, q = 5, 17  # mathematical names in the context of the question</code></pre>

        <p>In general, <code>i</code>, <code>j</code>, and <code>k</code> are the most common indices used.</p>


        <h3 id="o-and-l">'o' and 'l'</h3>


        <p>Do not use the letters 'o' and 'l' by themselves as names:</p>

        <blockquote>
          <p>Bad</p>
        </blockquote>

        <pre><code>o = O +