Finding "unknown" character references

Hi,

I need to check for "unknown" character references within my XML files.
All valid character references are stored in another XML file
("invalid_chars.xml") :

<?xml version="1.0" encoding="ISO-8859-1"?>
<chars>
   <char>&#8222;</char>
   <char>&#8218;</char>
   <char>&#353;</char>
   ...
</chars>

Everytime a special character, which is unknown to this reference file,
is encountered,
it should be outputted.


What I've come up with is:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="2.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:output method="xml" encoding="ISO-8859-1" indent="yes"/>

    <xsl:template name="init">
        <xsl:variable name="source" select="'../dirlist.txt'"/>
        <xsl:variable name="encoding" select="'iso-8859-1'"/>
	<xsl:variable name="src">
	    <errors>
	       <xsl:for-each select="tokenize(unparsed-text($source,
$encoding), '\r?\n')">
		<file>
		    <xsl:value-of select="."/>
		</file>
	        </xsl:for-each>
	     </errors>
	</xsl:variable>
	<xsl:result-document href="invalid_chars.xml">
	    <errors>
	         <xsl:apply-templates select="$src//file[text()]"/>
	     </errors>
	</xsl:result-document>
      </xsl:template>

      <xsl:template match="file">
	<xsl:analyze-string select="."
regex="^([0-9]{{2}}.[0-9]{{2}}.[0-9]{{4}})\p{{Zs}}+([0-9]{{2}}:[0-9]{{2}
})\p{{Zs}}+([0-9.]+)(.*)$" flags="ix">
    	      <xsl:matching-substring>
	            <xsl:variable name="docpath"
select="normalize-space(regex-group(4))"/>
	             <xsl:variable name="errors" as="element()*">

			<!-- Here my problems begin -->

			<xsl:if
test="document($docpath)//text()[contains(., '&amp;')]">
		   	      <xsl:analyze-string select="."
regex="&amp;[#a-zA-Z0-9]+" flags="i">
				<xsl:matching-substring>
			  	     <xsl:if
test="document('valid_cahrs.xml')//char=concat(regex-group(0), ';')">
					<file>
					    <char>
					         <xsl:value-of
select="."/>
					         <xsl:text>;</xsl:text>
					    </char>
					</file>
				      </xsl:if>
				</xsl:matching-substring>
			        </xsl:analyze-string>
			  </xsl:if>
		      </xsl:variable>

		      <xsl:for-each-group select="$errors"
group-by="@name">
			<file name="{current-grouping-key()}">
		   	     <xsl:for-each select="current-group()">
				<xsl:copy-of select="*"/>
			      </xsl:for-each>
			</file>
		       </xsl:for-each-group>
		</xsl:matching-substring>
	        <xsl:non-matching-substring/>
	   </xsl:analyze-string>
       </xsl:template>
</xsl:stylesheet>


Example XML:

<?xml version="1.0" encoding="ISO-8859-1"?>
<root>
     <absatz> &#8222;dyplom licencjata piel&#281;gniarstwa&#8220;
</absatz>
</root>


How can I check, if a text node contains a character unknown to my
valid_chars.xml?
Do you have any ideas, how I can make my XSLT work?
Thank you very much.

wbr,
Roman