This may be of interest to those who seek to know a little about the difference between the types of additions to the FS9 Scenery Library:- Terrain Mesh TM gives the sim an elevation matrix rather like a 3-D wire line graph so all heights/elevations of the terrain you see (hills, mountains, plains etc.) FS use this information to be able to display how high a piece of land is shown in height above sea level. You will see various different "LOD" values for the mesh files given in meters - these represent the distances in meters between each point or height (data) sampled to build the mesh elevation frame model. The lower this LOD value then the more accurate the terrain mesh model for your scenery in that particular area will be (i.e. there are more sampling data points for a given area). Adding terrain mesh will improve the accuracy and look of your higher elevation areas - mountains and gorges will look more like the real mountains and gorges. If you overlap or have two different LOD TM files for the one area active in FS9 then the sim will use the most accurate LOD value automatically irrespective of where you have it in the layers of your Scenery Library. Landclass LC basically tells the sim what type of scenery layer tile to place over or on top of that terrain mesh model, for example is it a heavily built up city tile that is required or a sparsely populated wooded area or a desert or a mountain area. Adding Land-Class will improve the accuracy and appearance of areas like cities, deserts and forested woodlands by placing them where they really are in real life. Scenery is I guess a term we give to a heavily detailed area that has been build especially to define the exact locations of buildings, bridges, famous landmarks (like statues ) runways, terminals etc. which are required to be as accurately laid out as possible. The most obvious are airports of course but you can and do have all sorts of areas defined as "scenery" like bush camps even without landing strips and those famous missing bridges of course!. Adding or changing the scenery will place new textures, constructions and buildings on those polygon tiles making the area hopefully look more like the real thing or at least making an improvement to the MS default textures and landmarks/facilities. Textures are the different "patterns" or "painted" tiles that sit rather like being draped over the Terrain Mesh to give the impression of a solid land surface with a characteristic look. Textures include all the rivers and roads for example.One point to remember is when adding scenery folders you always need to have the two sub-folders "Texture" and "Scenery" but most important when adding Terrain Mesh and/or Landclass you have just a "Scenery" sub-folder and NEVER put a "Texture" (even an empty one!) in there - if you do the sim won't use the Landclass or Terrain!. Better too to have all your Terrain Mesh folders lower down the priority list in your FS Scenery Library, Scenery layers up at the top of the stack and Landclass somewhere in between. TM and Landclass have to be activated the same way that you activate normal scenery in the Scenery Library - I plonk them all in my Addon Scenery folder and activate them from there. Hope this helps to explain it a bit. Dave

I recommend d/ling tmf_manual.zip, lwmtut.zip, ground2k_for_beginners_121649.zip and www.fs-traveler.com.scott s..

Thanks for taking the time Dave to explain all the different add-ons. I was pretty confused as to what was what before I read your post, and now it all makes sense.