data/pom/56.xml
<?xml version="1.0" ?>
<math type="pom-exported">
<expression prime-tag="sequence">
<term prime-tag="letter" secondary-tags="Latin">F</term>
<expression prime-tag="underscore" secondary-tags="subscript_operation">
<term prime-tag="letter" secondary-tags="Latin">r</term>
</expression>
</expression>
</math>