I am forced to put my grain of salt on this: For what I read, almost everybody is right above. When you play, you play in a session, and there is where all your rules are. In my case I use extensive rules to control all the points, AI trains and all. And that has to be made in a session. Let's say you make your route, put all the locos, cars, trees, set all the AI's and everything. And you play the runs to make sure everything works as you want. Now you save it and create the first session so you can play again from the point you stopped. (Do it by "do not save session" ???). Next day you come back and play the session as you left. But soon, you realize that you would like to have a tree here, more paint there.. and you want to add a siding (more tracks). If I go to the route, and add all that in the session, it will not show in the route. So, you go to the session and add there. The changes are in the session but not the route. You can merge the session to the route. If you go to the route and make the changes there, some of them will show in the session and others (splines), will be messed up in the session, and when you exit the session will in turn mess the route! Bottom line is that I need to have a base that I can modify and is sort of indestructible, and start sessions from there. You could say, "the hell with the route, stay in the session only", but if in the session, I modify rules, they don't "transport" to the route and I have to be modify there too. By now everything is complex, cloudy and a pain there. Again I have said this many times in other posts: Why not give the option of when you save the session, to add the changes in the route? And why not have the option of transporting the rules in the session, back to the route? That could be options as to what you want to do at the moment of saving. All this are general happenings, some people never have the problem and some others do! and those that don't experience these problems will negate the ones that have it! When N3V created the mess of layers, they should have made very clear how it all works, and if somebody say it was clear, please understand that some of us are more clever than others, and sooner or later somebody will look at it and say what I said above: "complex, cloudy and a pain there".