(forall (x) (P x (f x)))
=
<Forall>
   <Quantifier_vars>
      <Variables_list>
         <rdf_1 rdf:resource=“#var_1”/>
      </Variables_list>
   </Quantifier_vars>
   <Body>
      <Atomic_formula> … reference to #var_1 …
      </Atomic_formula>
   </Body>
</Forall>
<Variable rdf:ID=“var_1”>
   <name>x</name>
</Variable>