I created a tree navigation using XSLT from a sitemap for the homepage successfully (code below).

Now how do I create a tree navigation that start from some point by node id? for example i have this sitemap

Level1a

--Level 2a

----Level 3a

----Level 3b

--Level 2b

Level 1b

I want to create a tree navigation that just show from Level 2a and below (but not included Level 2b) like this:

Level 2a

--Level 3a

--Level 3b

Which line I have to change from the code that shows whole tree below? Thanks

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE xsl:stylesheet [ <!ENTITY nbsp "&#x00A0;"> ]>
<xsl:stylesheet
  version="1.0"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns:msxml="urn:schemas-microsoft-com:xslt"
  xmlns:umbraco.library="urn:umbraco.library" xmlns:Exslt.ExsltCommon="urn:Exslt.ExsltCommon" xmlns:Exslt.ExsltDatesAndTimes="urn:Exslt.ExsltDatesAndTimes" xmlns:Exslt.ExsltMath="urn:Exslt.ExsltMath" xmlns:Exslt.ExsltRegularExpressions="urn:Exslt.ExsltRegularExpressions" xmlns:Exslt.ExsltStrings="urn:Exslt.ExsltStrings" xmlns:Exslt.ExsltSets="urn:Exslt.ExsltSets"
  exclude-result-prefixes="msxml
 umbraco.library Exslt.ExsltCommon Exslt.ExsltDatesAndTimes
Exslt.ExsltMath Exslt.ExsltRegularExpressions Exslt.ExsltStrings
Exslt.ExsltSets ">


<xsl:output method="xml" omit-xml-declaration="yes" />

<xsl:param name="currentPage"/>


<!-- update this variable on how deep your site map should be -->
<xsl:variable name="maxLevelForSitemap" select="40"/>

  <xsl:template match="/">
<div id="sitemap">
<xsl:call-template name="drawNodes">  
  <xsl:with-param name="parent" select="$currentPage/ancestor-or-self::* [@isDoc and @level=1]"/>  
</xsl:call-template>
</div>
</xsl:template>

<xsl:template name="drawNodes">
<xsl:param name="parent"/>
<xsl:if test="umbraco.library:IsProtected($parent/@id,
 $parent/@path) = 0 or (umbraco.library:IsProtected($parent/@id,
$parent/@path) = 1 and umbraco.library:IsLoggedOn() = 1)">
  <ul id="gray" class="treeview"><xsl:for-each select="$parent/* [@isDoc and string(umbracoNaviHide) != '1' and @level &lt;= $maxLevelForSitemap]">


      <li>
      <a style="margin-left:3px;" href="{umbraco.library:NiceUrl(@id)}">
        <xsl:if test="$currentPage/@id = current()/@id">
          <xsl:attribute name="class">selected</xsl:attribute>
        </xsl:if>
        <xsl:value-of select="@nodeName"/>
      </a>

      <xsl:if test="count(./* [@isDoc and string(umbracoNaviHide) != '1' and @level &lt;= $maxLevelForSitemap]) &gt; 0">   
        <xsl:call-template name="drawNodes">    
          <xsl:with-param name="parent" select="."/>    
        </xsl:call-template>  
      </xsl:if>
      </li>        

    
</xsl:for-each>
</ul>
</xsl:if>
</xsl:template>

</xsl:stylesheet>