All of the clans have varied OS assigned to them based loosely on how I interpreted the daimyo's military leadership style in books I've read. Try a few clans and you'll see the differences.
Yes, I will do that in the "How To" guide in the second post in this thread.Thanks for that update Haz. I'm gunna play Chosokabe and try out Vassle OS. Maybe you could say in main page what the 9 main factions use as standard for a OS " Cosokabe uses Vassle OS, Shimazu and Mori use Clan OS, Hojo uses Provicial and the rest are Millatary OS." something like that, so numbnut people like me can just plug and play anyway I'm gunna give it a hammering all weekend.