XSLT: monitoring conversions wrt attributes and unhandled elements

monitoring-conversions.xsl

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
    xmlns:xs="http://www.w3.org/2001/XMLSchema"
    exclude-result-prefixes="xs"
    version="2.0">
    
    <xsl:template match="/">
        <!-- ATTRIBUTES IN USE -->
        <xsl:variable name="root-node" select="."/>
        <xsl:comment>
            LIST OF ATTRIBUTE PROPERTIES
            
            Take care when transforming
            
            Attributes in input file: <xsl:value-of select="count(*//attribute::*)"/>
            Distinct attributes in input file: <xsl:value-of select="distinct-values(*//attribute::*/name())"/>
            Distinct attribute values in input file: <xsl:value-of select="distinct-values(*//attribute::*)"/>
            Distinct attribute values by attribute:
            <xsl:for-each select="distinct-values(*//attribute::*/name())">
                <xsl:text>&#xa;- </xsl:text>
                <xsl:value-of select="."/>
                <xsl:text>: </xsl:text>
                <xsl:value-of select="distinct-values($root-node//attribute::*[name()=current()])"/>
                <xsl:text>&#xa;</xsl:text>
            </xsl:for-each>
        </xsl:comment>
        <xsl:apply-templates/>
    </xsl:template>
    
    
    <!-- XSL Templates -->
    <xsl:template match="*:elementA">
        <ul><xsl:apply-templates/></ul>
    </xsl:template>
    
    <xsl:template match="*:elementB">
        <li><xsl:value-of select="."/></li>
        <xsl:apply-templates/>
    </xsl:template>
    
    <!-- Warnings (element based) -->
    <xsl:template match="*">
        <ERROR>
            	<xsl:comment>
			<xsl:text>ERROR: element '</xsl:text>
			<xsl:value-of select="local-name()"/>
			<xsl:text>' not handled</xsl:text>
		</xsl:comment>
            	<xsl:apply-templates/>
            	<xsl:comment>
			<xsl:value-of select="local-name()"/>
		</xsl:comment>
        </ERROR>
    </xsl:template>
    
</xsl:stylesheet>