an class="special">-</span><span class="identifier">zA</span><span class="special">-</span><span class="identifier">Z</span><span class="special">]</span>
<span class="identifier">digit</span>      <span class="special">:=</span> <span class="special">[</span><span class="number">0</span><span class="special">-</span><span class="number">9</span><span class="special">]</span>

<span class="identifier">identifier</span> <span class="special">:=</span> <span class="identifier">letter</span> <span class="speci