Here and previously it just said "unfit for usual occupation", but lately companies are asking for more detail.
I suggest my medical problems are personal and none of their business but accept, if it affects my (usual) performance when I return they should be advised.
You know, one or two days off with a tummy bug doesn't affect your normal work, but loosing a leg might kind of reasoning.
Just asking what is the norm or accepted about the world and interested