A sequence from sequences

      <xsl:stylesheet
                  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                  version="2.0">
            <xsl:output  method="xml"
                        indent="yes"
                        omit-xml-declaration="yes"/>

            <xsl:template  match="/aaa">
                  <xxx>
                        <xsl:value-of  select="(),(1,2),3,((4,5),6)"/>
                  </xxx>
                  <yyy>
                        <xsl:value-of  select="(bbb[1],bbb[3]),(bbb[2],bbb[3]), (bbb[1],bbb[1])"/>
                  </yyy>
            </xsl:template>

      </xsl:stylesheet>

      <aaa>
            <bbb>b1</bbb>
            <bbb>b2</bbb>
            <bbb>b3</bbb>
      </aaa>

      <xxx>1 2 3 4 5 6</xxx>
      <yyy>b1 b3 b2 b3 b1 b1</yyy>