I am always in trouble about the retrain of my units. I would like to play as accurately as possible during my campaigns, but I don't know, to retrain for example a Pezhetairoi unit (trained in, say Antiochia) in the katoikias of Margiane, or Drangiane is accurate or not? All the same with the other, different cultures and factions. It would be incredible IMHO to have an accurate, little retrain guide or something like that.