Now reads:

"flat: forces one normal per flat part.
object: does not produce standard normals, but leaves the object-specific ones untouched.
sphere: forces normals to behave as the object would be a sphere."

Suggest with some questions:

"flat: one normal per flat part.

object: apply object-specific normals (I am assuming these are specified using other dr3d attributes on objects?)

sphere: normals behave as if an object is a sphere.