1 <e>

     2     <?pi1 data1?>

     3     <?pi2 data2?>

     4     <!-- comment1 -->

     5     <!-- comment2 -->

     6     <?pi3 data3?>

     7     <!-- comment3 -->

     8     <?pi4 data4?>

     9     <e2>

    10         <!-- comment1 -->

    11         <!-- comment2 -->

    12         <?pi3 data3?>

    13         <!-- comment3 -->

    14         <?pi4 data4?>

    15     </e2>

    16 </e>