Letters won't work. You don't assign an ID (essentially the number) to a model, the game does automatically. so no go for the letters.
You can add nation specific techs quite simple.
First you create a tech that does nothing. Don't make it researchable (no button to click on, I _guess_ that can be done by leaving out the 'position'-line. If not, pity.), then give the tech to the country specifically ( in the scenario file). Make all other nation specific techs require it.
You can add nation specific techs quite simple.
First you create a tech that does nothing. Don't make it researchable (no button to click on, I _guess_ that can be done by leaving out the 'position'-line. If not, pity.), then give the tech to the country specifically ( in the scenario file). Make all other nation specific techs require it.