quick tech tree question

[Level]

Everything should be in order. If you do find information that conflicts with the tree posted please tell me.

I found a few errors:
Steel is required for Artillery, Rifling is optional.[edit] but I guess that means both are required,Fixed.
Flight and Artillery are optional for Rocketry.
Satellites and Plastics are optional for Fiber Optics.
Plastics and Fission are optional for Ecology.

I did not see any others but there could be more.
Here is a quick (MS Paint) correction:

 

[Crayton]

Thank you very much for taking the time to cross-reference the tech-tree. I know people appreciate the attention to detail.