We refer to a fourth-gen airplane as a multi-role fighter that the services have used in a fairly service-specific role. It did not include the technologies of stealth, it did not include the technology of integrated avionics, and it wasn't designed with the intent of being an interoperable fighter. We've taken those fighters and had to use them in coalition operations, but they don't interoperate very well.
So one of the fundamental differences with a fifth-gen airplane is that the airplanes will all operate with each other. In many ways, it's like your laptop when you plug into the Internet. These airplanes will be nodes on the battle space internet in terms of information flow in the future.
We've also integrated in that the dimension of stealth, which gives a tactical advantage of surprise, and we've integrated into that advanced sustainment techniques to try to drop the cost of owning these airplanes.