A full manual will simply not be possible nor available before the final release of TG2 later this year. In the meantime partial documentation available here, along with the support and discussion forums where Planetside staff answer questions, and input and tutorials from the public will have to do.
The open and flexible nature of TG2 means that in many cases few shaders are *not* able to be used in particular areas or ways. Certainly there are things that cannot or should not be used in the Terrain or Shaders groups, for example Camera or Lighting nodes, but for the most part you can use almost any other shader in either area, and this is *by design*. I think in many cases part of the problem is people want structure where there may not be any, guidelines where none may be possible. At the same time many people want great flexibility, which is why the system is designed this way to begin with.
That being said there are general guidelines that can and should be adhered to. The Terrain group is for making major terrain structures and shapes. Any significant displacement should be handled there, generally speaking. However no color comes out of this group. This is what the Shaders group is for - primarily to provide color and other surface properties (including smaller-scale displacement). So this is a general guideline on division of work and functions of nodes between the two sections. But this does not mean necessarily that one or other type of shader cannot be used in either area, it is more the intention of your specific use of the shader that matters, not the type of shader itself.
- Oshyan