What is it?

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet 
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns:cda='urn:hl7-org:v3' 
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  version="1.0">
  <xsl:template match="/|cda:*|@xsi:type|text()|@*">
    <xsl:copy>
      <xsl:apply-templates select="cda:*|@*|text()"/>
    </xsl:copy>
  </xsl:template>
</xsl:stylesheet>

What is this small but useful beast?