es_sort.xslt

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output omit-xml-declaration="no" indent="yes" encoding="UTF-8"/>
 <xsl:strip-space elements="*"/>

<xsl:template match="systemList">
<systemList>
  <xsl:for-each select="system">
   <xsl:sort select="fullname"/>
<system>
<xsl:copy-of select="*" />
</system>

</xsl:for-each>

</systemList>
</xsl:template>
</xsl:stylesheet>