Hi, makman!
Sorry for my absence.
Not important, you can delete it. This is remnant from my own file, that I forgot to delete before release.
In detail:
When I searched for grid colors and found where are stored, there have these four colors:
The fourth have the same values like the second one, but I don't found for what it is. By changed it, nothing happens, visualy on the map. So, maybe is something unused, but anyway it is not something that I will spend time to investigate and search.
So, delete it, I just forgot to do that!