I have a skydome with a simple planar map on an additional UV set so that I can lerp between a horizon and zenith color using simple vector3 nodes.
Problem is, only way I can find to assign UV sets is from within a texturecoordinate node and a vector3 node has no UV coord input.
The workaround is simple. Swap the UV channels in Maya and re-export the mesh.
But the question remains as it would be nice to have this knowledge.
Related: How do I disable sRGB for my vector3 nodes? I don’t like the effect it has on my atmosphere colors.