Hi,

I just discovered something rather cool, some techs can appear randomly in your game. The 4 'books of' techs for example may or may be not in your game.

Now, this asks 2 questions. It seems to be governed by 2 data:

<Rarity>25</Rarity>

<AppearanceChance>25</AppearanceChance>

First question, why the 2 data are always same. Is one obsolete? 

Second question, with 25% chance, why do I routinely gets 3 out of the 4 books. Are the odds erroneously calculated? Should I understand the 25 as the chance to NOT have the book instead of having it?

Thanks for your answers. Anyway, I see a lot of interest in this feature, with new dead-end 'mini techs' only giving one optional item that won't cripple you if you don't get it (typically a minor magic item or a minor spell).