Miva - Loop Over String's Characters
<mvt:assign name="g.string" value="'Hello World!'" />
<mvt:while expr="g.counter LT len(g.string)">
<mvt:assign name="g.counter" value="g.counter + 1" />
<mvt:eval expr="substring_var( g.string, g.counter, 1 )" /><br>
</mvt:while>