Recursive XSLT: Concat Multiple Nodes

Sharing this XSLT which I used couple of years back to concat a node set. The usecase was to extract a specific node set and concatenate their values.

Sample Input:

<root>
    <node>
        <data>123</data>
        <data>456</data>
        <junk>abc</junk>
    </node>
    <junknode>
        <junk>def</junk>
    </junknode>
    <node>
        <data>789</data>
        <junk>ghi</junk>
        <data>012</data>
    </node>
</root>

Desired Output:

<out>
  <mssg>123456789012</mssg>
  <junk>abcdefghi</junk>
</out>

XSLT:

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
  <xsl:output indent="yes" />
  <xsl:template match="/">
    <out>
      <xsl:variable name="mssg_data">
        <xsl:call-template name="ConCat">
          <xsl:with-param name="List" select="/root/node/data" />
        </xsl:call-template>
      </xsl:variable>
      <xsl:variable name="junk_data">
        <xsl:call-template name="ConCat">
          <xsl:with-param name="List" select="//junk" />
        </xsl:call-template>
      </xsl:variable>
      <mssg>
        <xsl:value-of select="$mssg_data" disable-output-escaping="no" />
      </mssg>
      <junk>
        <xsl:value-of select="$junk_data"/> 
      </junk>
    </out>
  </xsl:template>
  <xsl:template name="ConCat">
    <xsl:param name="List" />
    <xsl:param name="result" select="''" />
    <xsl:choose>
      <xsl:when test="$List">
        <xsl:call-template name="ConCat">
          <xsl:with-param name="List" select="$List[position() &gt; 1]" />
          <xsl:with-param name="result" select="concat($result, $List[1])" />
        </xsl:call-template>
      </xsl:when>
      <xsl:otherwise>
        <xsl:value-of select="$result" disable-output-escaping="no" />
      </xsl:otherwise>
    </xsl:choose>
  </xsl:template>
</xsl:stylesheet>

Note: The similar result can be achieved by using XPATH evaluator to get text of data node set (ie /root/node/data/text()), depending on the requirement one or the other approach may be more suitable.