hi im using this xslt to generate my menu, but i dont want certan files appering in the menu, how easy is it to do?

<?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"
  exclude-result-prefixes="msxml umbraco.library">
    <xsl:output method="xml" omit-xml-declaration="yes" />
    <xsl:param name="currentPage"/>
    <!-- Input the documenttype you want here -->
    <xsl:variable name="level" select="1"/>
    <xsl:template match="/">
 <ul id="topNavigation">
       <li class="home">
         <xsl:if test="$currentPage/@id = $currentPage/ancestor-or-self::* [@level=$level]/@id">
             <xsl:attribute name="class">home current</xsl:attribute>
         </xsl:if>
         <a href="/">Home</a>
       </li>
      <xsl:for-each select="$currentPage/ancestor-or-self::* [@level=$level]/* [@isDoc and string(umbracoNaviHide) != '1']">
  <li>
     <xsl:if test="contains($currentPage/@path,@id)">
        <xsl:attribute name="class">current</xsl:attribute>
      </xsl:if>
    <a href="{umbraco.library:NiceUrl(@id)}">
      <span><xsl:value-of select="@nodeName"/></span>
    </a>
  </li>
</xsl:for-each>
</ul>
    </xsl:template>
</xsl:stylesheet>