unfortunately when transforming the i'th 'a' element to a 'b' (assume i > 1) I also need to access the (i-1)'th 'b' element; that is, the values used to create a 'b' element are dependent upon the current 'a' element being transformed and the preceding 'b' element. Is this possible? in a single pass?

<xsl:template name="b-from-a">
  <xsl:param name="local-a" />
  <xsl:choose>
    <xsl:when test="not($local-a)">
      <!-- Shouldn't be reached unless your initial call is bogus. -->
    </xsl:when>
    <xsl:when test="$local-a/preceding-sibling::a[1]">
      <xsl:variable name="prev-b">
        <xsl:call-template name="b-from-a">
          <xsl:with-param select="$local-a/preceding-sibling::a[1]" />
        </xsl:call-template>
      </xsl:variable>
      <!--
           Use $local-a and $prev-b to construct "b"
      -->
      <xsl:value-of select="..." />
    </xsl:when>
    <xsl:otherwise>
      <!--
           First occurrence (i == 1)
           Construct it however you normally do it.
      -->
      <xsl:value-of select="..." />
    </xsl:otherwise>
  </xsl:choose>
</xsl:template>

Greg Faron
Integre Technical Publishing Co.