Excludes are bgl files that tell the sim not to load stock shorelines, runways etc.
They can be found in many add-on scenery packages. I find it's good practice to have them as a separate scenery layer, lower down the listing than the add-on sceneries.
I usually put them all in a single scenery folder, just above any mesh layers, but below any add-on scenery layers.
Having them in a separate layer makes sure the sim processes the excludes BEFORE drawing the add-on scenery.
The filenames are usually self-explanatory, so if you see anything like "### vtp_exclude.bgl", or "0xcl_###.bgl", they're scenery exclude files.
Naming them "0xcl_###" is just a G2K naming convention. The "0" should mean it's loaded before any other bgls in the folder it's in, which is why you can find them amongst the files for a lot of older sceneries.
But I've found that this method can occasionally be unreliable, which is why I now prefer to load excludes through a separate scenery layer in the hierarchy.
Hope this makes some sense.
