title: xslt document function question
body: <p>If one is using the document function and opening up files that might not exist e.g.</p>
  
  <pre><code>&lt;xsl:variable name="input" select="document($A)/document/input"/&gt;
  </code></pre>
  
  <p>what is the graceful way of handling the error?  I would like a default value for the variable if the file can't be opened.</p>