e limited to what can be foreseen before compilation. A
  somewhat related library, the boost::spirit parser framework, allows for
  roughly the same runtime configurability.</p>

  <h2><a name="ErrorHandling" id="ErrorHandling">Error handling</a></h2>

  <p>There is not a single word about error handling in the UML state machine
  semantics specifications. Moreover, most existing FSM solutions also seem
  to ignore the issue.&nbsp;</p>

  <h3>Why an FSM library should support error handling</h3>

  <p>Cons