From the Product page: "The Highlight and contour maps were designed with a very specific look in mind. Highlights have been preserved in the maps in order to compensate for certain renderers that do not accurately represent specular effects. They are useful in global lighting situations or when you are wanting a simple solution to lighting your Vicki 3 character.[..]" It is clearly mentioned that the highlights are on the map. There is another set of maps - Victoria 3.0 Universal Texture Maps - that is made without HighLights.

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