title: How to check if variable is Null or empty in XSLT?
body: <p>I definded the following variables:</p>
  
  <pre><code>&lt;xsl:variable name="pica036E"
                          select="recordData/record/datafield[@tag='036E']" /&gt;
  &lt;xsl:variable name="pica036F"
                          select="recordData/record/datafield[@tag='036F']" /&gt;
  </code></pre>
  
  <p>Now I need to do a condition if variable pica036E isn't empty and pica036F is empty show the following message otherwise show another message.
  That's my code, but I don't ge any output. Is "null or empty" correct defined?</p>
  
  <pre><code>&lt;xsl:choose&gt;
                          &lt;xsl:when test="$pica036E != '' and $pica036F = ''"&gt;
                          &lt;xsl:message&gt;
                           036F no 036E yes      
                              &lt;/xsl:message&gt;
                          &lt;/xsl:when&gt;
  
                           &lt;xsl:otherwise&gt;
                          &lt;xsl:message&gt;
                                  036E no 036F yes
                              &lt;/xsl:message&gt;  
                          &lt;/xsl:otherwise&gt; 
                      &lt;/xsl:choose&gt;  
  </code></pre>