well, its pretty complicated, and as far as I can see the actual decision making is coded into the game itself, but the files in AI0001.RFH seem to contain the instructions for executing strategies once the decisions are made. I've managed to get my custom units used by the AI by adding them to objectsets.txt. If anyone's interested I've posted what I've figured out so far on my website (http://www.btinternet.com/~mcatamneysanders/emperor/index.htm) and will be adding to this as I figure out more of it.