Thanks guys for the gen above. My interest really is at the end-user stage, I have no input at all (well, not at the moment anyway) on this system. Having heard it was underway, I just have some concerns that we will simply get the cheapest solution i.e. a bastardised TCAS/IFF which I still think will come with several potentially serious issues when they try and move it into the fast-jet/LL environment.