Unless you actually want to use a DEM or create one you will not really need them. There are about 6-7 main ones and they are used to represent different things on a DEM create file. There are quite a few DEM files (mainly for the US) created by fishlipsatwork kuid 59012 on the DLS.
You can download these and then create your own layout. Each colour means different things;
Red = Roads, Big line = big road, small line = small road
Blue = Rivers, Shorelines
Black = Political Boundaries, (counties etc.)
Teal = Rail lines
Light green = Small streams
If you need any help post again, I have all the textures and can email them to you, this may be easier then getting them off TrainzLuvr. Though it sounds like you may already have them.
Craig

