Does your company/supervisor have the right to request medical facts on the doctor's note to return to work?

Is it ethical or legal for a company to request medical facts on doctor's note or that of an attending licensed medical person for doentation of an employee's absence from work-- according to this company this is the definition: medical facts are a description of a condition that identifies the cause or nature of the illness or injury (i.e., viral illness, internal bleeding, back pain, upper respiratory infection). A procedure that identifies the body part (i.e., hysterectomy, appendectomy, tonsillectomy) is sufficient information to serve as a "medical fact". Terms such as "under my care", "surgery", or "stress" are not acceptable as medical facts. Medical facts do not require a diagnosis. Exactly what should be acceptable and what about doctor/patient confidentialty.