For each of the <em> elements, I am trying to get a space-delimited list
(or string) of attribute names. For example, the first one would be
"italic" and the second would be "italic bold". My output would be
similar to this:

<?xml version="1.0" encoding="UTF-8"?>

<root>

<p>

<em class="italic">first paragraph</em>

</p>

<p>

<em class="italic bold">second paragraph</em>

</p>

</root>

  <xsl:template match="em[@*]">
      <em class="{@*/name()}">
          <xsl:apply-templates/>
      </em>
  </xsl:template>