Should be used when using Maximum Value or Maximum Opacity. Diffuse Coefficient - how strongly the surface will appear illuminated by diffuse light. Specular Coefficient - how much of mirror like appearance the surface will have. Specular power - how sharp the specular reflection will be. Higher number gives a sharper, smaller area of specular reflection on a convex surface.
Lower number gives the surface a more matte appearance.
Transmit Coefficient - how transparent the object is. Transmissitivity - this is the fraction of light that is blocked per unit length along a ray passing through the volume. Index of refraction - how the light is refracted through a transparent object. There can only be one cut per object, and the only type is Simple Box Cut in version 2.1 of VolVIs. The color and shading of the surfaces cut by the box can be modified with the Color and Shading buttons.