Disability evaluations after injuries:

(a) Explain the following terms: "duration of disability" and "degree of disability".

(b) Explain how degrees of disability after injuries are assessed for the following conditions:

a. A unique injury for a worker who was well before the injury

b. Multiple injuries affecting the same organ or functional system

c. Injuries which are coexistent and do not have any functional correlation

d. A fresh injury sustained by a worker after a pre-existing incapacity