L4 implementations

[Shams]

Hi

I played with the demo cd and it works great..

Just a few questions which I am having a hard time understanding:

1. L4 is itself a API/ABI reference, right?

2. Are L4.Pistachio and L4.Fiasco are 2 different implementations of L4?

3. Is L4.Pistachio is the current official reference implementation?
Do both of them only differ in internal code only?

3. What is the difference between L4.Pistachio and L4.Fiasco?
Why are there 2 separate implementations ie. why not just one codebase?
Are you able to merge these 2 together or plan to?

4. Is L4.Sec official and already in the process of being implemented?
Is L4.Pistachio and L4.Fiasco going to be replaced by L4.Sec?

Thanks
Shams