<mvt:assign name="l.my_value" value="10" />
<mvt:assign name="l.settings:counter" value="0" />
<mvt:while expr="l.settings:counter LE l.my_value">
The value of counter is: &mvt:counter; <br>
<mvt:assign name="l.settings:counter" value="l.settings:counter + 1" />
</mvt:while>