The map is designed for bump and normal mapping with advanced settings. The map allows you to mix two source maps.
Primary & Secondary
Main and additional maps. The additional map changes the normals in the space of the first map, i.e. "turns" them.
Map
Source map with height data or normals.
Height
Additional height map.
Normal map input
Specifies the type of source map - it can be a height map or a normal map.
Mip-map usage
The amount to use mipmap levels for source maps.
Spot width
All calculations are performed in a small area determined by the diameter of the tracing ray (Ray differential). This setting allows you to reduce the spot.