Function use in XSLT version 1.0

xsl:function does not exist in XSLT 1.0. Use a xsl:template with name attribute or upgrade the stylesheet version to 2.0.

Incorrect:

  <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
    <xsl:output encoding="UTF-8" method="xml"/>
    <xsl:function name="my:foo">
      <!-- body logic -->
    </xsl:function>
  </xsl:stylesheet>

Correct:

  <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
    <xsl:output encoding="UTF-8" method="xml"/>
    <xsl:template name="foo">
      <!-- body logic -->
    </xsl:template>
  </xsl:stylesheet>

or:

  <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="2.0">
    <xsl:output encoding="UTF-8" method="xml"/>
    <xsl:function name="my:foo">
      <!-- body logic -->
    </xsl:function>
  </xsl:stylesheet>