Before revision:  The challenge in this setting, when no modelspecification for these securities nor for the death timeis given, lies in finding the dynamics and the structures for the mortality / longevity securities used in the securitization.
After revision:  The challenge in this setting, when no modelspecification for these securities nor for the death timeis given, lies in finding the dynamics and the structures for the value processes of defaultable or mortality and / longevity securities used in the securitization.