navigation, TEI

Dear List!

I'm working on extending the TEI xsl stylesheet set with a more
complex 'prev-next' navigation bar. For the linking i need two
parameters: the text of the link, and the id of the link.
I use a template to get the appropriate node:

<xsl:template name="getPrev">
  <xsl:variable name="nodeSet">
    <xsl:text>self::div0 | self::div1 | self::div2 | self::div3 | 
self::div4</xsl:text>
  </xsl:variable>

  <xsl:choose>
    <xsl:when test="(preceding-sibling::*[$nodeSet]/head)[last()]">
      <xsl:copy-of select="preceding::*[$nodeSet]/head[last()]" />
    </xsl:when>
    <xsl:when test="(ancestor::*[$nodeSet]/head)[last()]">
      <xsl:copy-of select="ancestor::*[$nodeSet]/head[last()]" />
    </xsl:when>
    <xsl:otherwise></xsl:otherwise>
  </xsl:choose>
</xsl:template>

and i call this with:
<xsl:variable name="previous">
  <xsl:call-template name="getPrev" />
</xsl:variable>

but as i would like to get the id of the node the following code doesn't work:

  <xsl:variable name="previousID">
    <xsl:value-of select="generate-id( $previous )" />
  </xsl:variable>

with the xsl processor saying: 'generate-id() : invalid arg expecting a 
node-set'
So i have to write another template (getPrevID) with the only difference of the 
selection:
  'select="generate-id( ... )"'

and the xpath expression
  (preceding-sibling::*[$nodeSet]/head)[last()]
is the same than this:
  (preceding-sibling::*/head)[last()]
the $nodeSet variable doesn't work at this situation.

I use the 'xsltproc.exe' program shipped with TEI-Emacs.

Have you got any idea to solve these problems?

Thanks,

kiraly peter
http://www.arcanum.hu