Anisotropic filtering level of the texture.
Anisotropic filtering makes textures look better when viewed at a shallow angle, but comes at a performance cost in the graphics hardware.
Usually you use it on floor, ground or road textures to make them look better.
The value range of this variable goes from 1 to 9, where 1 equals no filtering applied and 9 equals full filtering applied. As the value gets bigger, the texture is clearer at shallow angles. Lower values mean the texture will be more blurry at shallow angles.
See Also: texture assets.