Location: file:///Applications/Unity/Unity.app/Contents/Documentation/html/en/Manual/class-LODGroup.html

Text: "The choice of Fade Mode determines how one LOD level is blended into the next. The value calculated by the LOD system is passed as a parameter to the shader that renders the mesh."

Should include info that Yao posted in Alpha group (at least a part of that info): LOD fading currently provides the "blend factor" in unity_LODFade.x. It's actually a float2 uniform and its .y component is the same value in .x but only be quantized into 16 levels.

Further info from his posting (might also be relevant for documentation): But LOD won't automatically get switched smoothly. It's up to you to implement a smooth transition algorithm and Unity will provide a proper blend factor according to the camera settings (e.g. distance) for you to use in your shader. Speedtree shader is one sample to check out (SpeedTree stores two positions in one vertex: one is the model-space vertex position and the other is the position of the same vertex in the next LOD. It uses unity_LODFade.x to lerp between the two positions to achieve smooth transition effect).

See also alpha group: https://groups.google.com/d/topic/unity-alpha-testing/yLVZxEq0vKs/discussion

While you're at it - there's also a typo in there. A "u" is missing in "updates": "The Lightmap Scale button pdates the Scale in Lightmap property"