Dear Hulfgar, I read all night what you wrote plus the code. Just to say my conclusions: 1.the values like tech required for a unit or resource needed (in units.xml) are easily edited and I have no problem in this.Same in unit classes. 2.I have edited the original files of the game.There is no going back now,cause a lot of staff needed to this game,and I have to reinstall the game in order to reverse all the changes I have made(which is impossible). 3.I considered that ship of the line for example,should be available to all civilizations,not just the English one.And what I did to be available to all?I simply copy the code for ship of the line,then create a new class for it and all done.The art files path was already there ,so there was no need for further changes.I m telling you this as an example. 4.From the above,i haven't understood,perhaps I m stupid,my brain cpu is definately lower than yours,how to create my own mod.i can only edit xml files. 5.Therefore,can you please make this mod with the ship?,and then I ll try just copy it,cause I want to use a unit from your mod(the early jet fighter),and if you can do this mod with this ship,i think that I will have an example,about the future.Its up to you,no problem if you cant do this.