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<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" 
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                xmlns:exsl="http://exslt.org/common"
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    <xsl:key name="nodes" match="/Message/Body/Changes/Data/*" use="local-name(.)" />

    <xsl:template match="/">
        <xsl:for-each select="/Message/Body/Changes/Data/*[generate-id(.)=generate-id(key('nodes', local-name(.)))]">
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</xsl:stylesheet>