In this paper, the authors clarifies the relationships between security notions for broadcast encryption. In the past, each new scheme came with its own definition of security, which makes them hard to compare. The authors thus define a set of notions, as done for signature and encryption, for which they prove implications and separations, and relate the existing notions to the ones in their framework. They find some interesting relationships between the various notions, especially in the way they define the receiver set of the challenge message. In addition, they define a security notion that is stronger than all previous ones, and give an example of a scheme that fulfills this notion.