Don't name it Class:: - such names usually refer to modules that make object orientation easier - i.e. writing classes (the notable exception being Class::Path, which IMHO is badly named).

Also most classes implement compound data types in some sense, so that alone shouldn't be your naming criterion.

So, name your class after the field it works in, and after what it does. Without knowing specifics it's hard to give general advise, except to look at existing CPAN root namespaces and try to re-use them where appropriate.