> Is there a solution that works in the Microsoft implementation?
don't know.

> Is there a way to do this in the current draft without using variables?

why no variables?
Anyway this solution uses one variable and produces

  bash-2.01$ xt u.xml ns.xsl

  [[nodeA]]
  
  [[nodeB]]
  
  [[nodeC]]
  
  [[nodeD]]
  bash-2.01$ 

on your sample input.

David


<xsl:stylesheet 
  xmlns:xsl="http://www.w3.org/XSL/Transform/1.0" 
  result-ns="">

<xsl:template match="root">
  <xsl:apply-templates select="*"/>
</xsl:template>

<xsl:template match="*">
  <xsl:variable name="x" expr="qname(.)"/>
  <xsl:if test="not(from-preceding-siblings(*[qname(.)=$x]))">
  [[<xsl:value-of select="qname(.)"/>]]
  </xsl:if>
</xsl:template>

</xsl:stylesheet>


 XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list