XML Tutorial/XSLT stylesheet/current group

value-of select="current-group()" separator=", "

File: Data.xml
<?xml version="1.0"?>
<list>
 <description>XPath 2.0 Context Functions</description>
 <date>2003-08-26</date>
 <function type="new">context-item()</function>
 <function type="new">current-date()</function>
 <function type="new">current-dateTime()</function>
 <function type="new">current-time()</function>
 <function type="new">default-collation()</function>
 <function type="new">implicit-timezone()</function>
 <function type="legacy">last()</function>
 <function type="legacy">position()</function>
</list>

File: Transform.xslt
<?xml version ="1.0"?>
<xsl:stylesheet version="2.0"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output method="xml" indent="yes" />
  <xsl:template match="list">
    <xsl:copy>
      <xsl:for-each-group select="function" group-by="@type">
        <functions type="{@type}">
          <xsl:value-of select="current-group()"
            separator=", " />
        </functions>
      </xsl:for-each-group>
    </xsl:copy>
  </xsl:template>
</xsl:stylesheet>
Output:
<?xml version="1.0" encoding="UTF-8"?>
<list>
   <functions type="new">context-item(), current-date(), current-dateTime(), current-time(), default-collation(), implicit-timezone()</functions>
   <functions type="legacy">last(), position()</functions>
</list>