while Function

Repeats a set of expressions until a condition is met. The first subexpression is called the conditional and will be evaluated each time through the loop. The loop terminates when the conditional is logically false. The value of the while expression is the value of the last expression in the loop during the last iteration.

Example

The following expression returns null.

<while>
    <gt>
       <ref>counter</ref>
      <i>0</i>
    </gt>
   <set name=’counter’>
      <sub> <ref>counter</ref>
         <i>1</i>
       </sub>
   </set>
</while>