title: comma operator in xpath, is it like c?
body: <pre><code>    &lt;xsl:variable name="html-output-name" 
           select="(if(@index and @index eq 'true') 
               then concat($default-name, '.html') 
               else (), 
           @html-output-name,
           @output-name, 
           $default-html)[1]" /&gt;
  </code></pre>
  
  <p>I see what the 'if' is doing, but I'm not sure how to make sense of the rest of the items in the command, and then the [1] at the end. Does this add up to 'the first non-empty item in the list?"</p>