It seems:
Anisotropy - 0/1 for blending into and out from the anisotropy shader
Tangent - XY is remapped from 0/1 to -1/1, and specifies the direction of the anisotropy. I assume RG is masked from all other inputs.
From there, normal maps can alter the angle of the effect (better to think of it as actually deforming the mesh into a new angle) while roughness controls the size. For some reason, I can’t achieve the stretched “brush metal” look with the specular highlights, it’s only stretching the images.