I use xsl version 2 to transform xml data
This is the input xml file

<?xml version="1.0"?>
<csv xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
   <line>
      <field>210.84</field>
      <field>0</field>
      <field>1</field>
      <field>2</field>
      <field>3</field>
   </line>
   <line>
      <field>210.84</field>
      <field>0</field>
      <field>1</field>
      <field>2</field>
      <field>3</field>
   </line>
   <line>
      <field>210.84</field>
      <field>6</field>
      <field>5</field>
      <field>4</field>
      <field>3</field>
   </line>
   <line>
      <field>210.84</field>
      <field>6</field>
      <field>5</field>
      <field>4</field>
      <field>3</field>
   </line>
   <line>
      <field>210.84</field>
      <field>6</field>
      <field>5</field>
      <field>4</field>
      <field>3</field>
   </line>
</csv>

We need to get the DISTINCT values in the field[2] in each element
<line>
We have for this example two distinct value which are 0 and 6 in the
elements <field[2]>. We need to have an output for these distinct
values and the two elements following them. The output should be:

<?xml version="1.0"?>
<csv xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
   <line>
      <field>0</field>
      <field>1</field>
      <field>2</field>
   </line>
   <line>
      <field>6</field>
      <field>5</field>
      <field>4</field>
   </line>
</csv>