This article explains the settings and values for the Scatter Edge Trimming shader in Cinema 4D.
Overview
The Scatter Edge Trimming shader allows you to trim scattered instances consisting of multiple mesh elements so that they stay within the boundaries of the distribute-on objects or the include/exclude splines. In addition to making the scattering look more refined and natural, this feature also provides a performance increase - thanks to removing some of the instances, you can save RAM and make parsing time shorter.
To learn more, see also:
Alternatively, you can use the Edge Trimming feature instead. When enabling the Edge trimming feature, there's no need to use the Edge Trimming Shader
Shader properties
Default shader – If a material is using some opacity texture in addition to the Scatter Edge Trimming shader, this texture can be defined here.
Example