In other words, should I name my class AcmeBundle\ETL\Transform or AcmeBundle\Etl\Transform?
EDIT
I found examples in the symfony core code to follow either case:
Symfony\Component\HttpFoundation (HTTP)
Symfony\Bridge\Monolog\Handler\FirePHPHandler (PHP)
In the end, I went with StudlyCase in my code.
If code guidelines exist for this framework, it would be worth asking for advice from the core contributors. You could do so on the devs mailing list, which may lead to a clarification in the written guidelines themselves.