ndles <code>??xleft</code> and <code>??xright</code>, 
with <code>??</code> being the label for the symbol.
</p>

<p>

<a name="action_part"></a>
<h5>2.5.2 User Actions</h5>
Actions appear in the right hand side as code strings (e.g., Java code inside
<tt>{:</tt> ... <tt>:}</tt> delimiters).  These are executed by the parser
at the point when the portion of the production to the left of the 
action has been recognized.  (Note that the scanner will have returned the 
token one past the point of the action si