Classes
A class system has been confirmed. The developers have been keen to emphasise that the class system will be very free-form and unrestrictive.
Matt Higby suggested that classes will enable players to recognise enemies more easily, and give players a better idea of their role in the battle. All classes will have significant scope for personalisation and specialisation.
Confirmed classes
This list has been suggested in a Q&A but is not necessarily complete, accurate or final:
Mutual Exclusivity
We know that healing and repair will be done by two distinct classes, probably medic and engineer respectively.[1] This means, for instance, you will not be able to both heal and repair at the same time.
References
1. Matt Higby - via Reddit
page revision: 5, last edited: 30 Jul 2012 02:24