Open Class Action and Beneficiaries

At the moment, there are two class actions against VET.
One by Slater & Gordon and other one by Maurice and Blackburn.
One by Maurice and Blackburn is open class action.
In open class action,does any one who has the right to participate in the class action,but not participate in the class action through the law firm or the class action fund offered,can get benefit when class action won or not?
Please explain the open class action and the beneficiaries!