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

  <stx:template match="/root">
    <stx:process-children/>
  </stx:template>

  <stx:template match="processing-instruction('pi')[1]">
    <stx:text>OK</stx:text>
  </stx:template>

  <stx:template match="processing-instruction('pi')[2]">
    <stx:text>FAILED1</stx:text>
  </stx:template>

  <stx:template match="processing-instruction()">
    <stx:text>FAILED2</stx:text>
  </stx:template>
  
</stx:transform>