[XSL]Selecting Sibling from the Top of the Tree

   <xsl:template match="book">
               <div>
           <p>
               <span class="booklist">
        Topic:
                   <xsl:call-template name="print"/>
               </span>
           <xsl:apply-templates/>
</xsl:template>

               <xsl:choose>
           <xsl:when test="count(ancestor::subject) &gt; 1 ">
               <xsl:if test="preceding-sibling::subject !=''">
                   [Also Used for:
           <xsl:value-of select="."/>]
               </xsl:if>
               <xsl:if test="following-sibling::subject !=''">
                   [Also Used for: <xsl:value-of select="."/>]
                </xsl:if>
               <xsl:value-of select="id(@topic)"/>
           </xsl:when>
           <xsl:otherwise>
               <xsl:apply-templates select="id(@topic)"/>
           </xsl:otherwise>
       </xsl:choose>
   </xsl:template>

[---------- The portion is in the header section 6 levels away from the <book>
<topicList>
<subject xml:id="tech">Technology</subject>
<subject xml:id="res">Resource</subject>
<subject xml:id="progr">Programming Language</subject>
</topicList>
--------------]