Okay, I must tell you the whole thing:
>NiTriStrips - your mesh
NiIntegerExtradata >Describes Normal Map Index (NRML)
NiIntegerExtradata >Describes Specular Intensity Index (SPEC)
NiIntegerExtradata >Describes Environmental Map Index (ENV_MASK)
NiIntegerExtradata >Describes Environment Intensity Index (ENV)
>NiTexturingProperty
NiSourceTexture DIFF - this is the base texture
NiSourceTexture ENV - this is the texture for Environment Intensity, so to the place where shader activated
NiSourceTexture NORMAL - This shows the "normal" intensity, where shader gets its intensity in several parts of the mesh (ex. blue = not really shiny | purple = shiny)
NiSourceTexture SPEC - Specular intensity shows the places where shader must be different than elsewhere (ex. mouth, face, hair, eyes)
NiSourceTexture EMSK - Shadow Shaders, and the same as SPEC
These are which needed to have a good shader.
How to add an Environmental Intensity Index (ENV):
First thing is to go to the mesh's base LH, and select the base mesh's NiTexturingProperty, then Copy Branch (Ctrl+C in newest NifSkope) and go to your mesh select NiTriStrips and Paste Branch (Ctrl+V in newest NifSkope)
And the rest about TLeaderheadShaderNoSkin_20
That's all about description. Hope you'll understand.