<stx:transform version="1.0" 
  xmlns:stx="http://stx.sourceforge.net/2002/ns"
  strip-space="yes">

  <stx:template match="node[@id=1]">
    <r avt="1+2">
      <stx:attribute name="att-{name()}" select="10 - 9"/>
      <lit a1="{1+2}" a2="1+2={1+2}" a3="{concat('a',1+1)}/b{position()}"/>
    </r>
  </stx:template>
  
</stx:transform>