lback functions used to handle errors for a validation context</p>
<div class="variablelist"><table border="0"><col align="left" /><tbody><tr><td><span class="term"><i><tt>ctxt</tt></i>:</span></td><td>a Relax-NG validation context</td></tr><tr><td><span class="term"><i><tt>err</tt></i>:</span></td><td>the error callback</td></tr><tr><td><span class="term"><i><tt>warn</tt></i>:</span></td><td>the warning callback</td></tr><tr><td><span class="term"><i><tt>ctx</tt></i>:</span></td><td>contextual data for the