In HKSAR v S Space Design (HK) Co Ltd (1997), McMahon, J said: "On the face of Section 15 [of the Employment Ordinance], its terms are plain and unambiguous. It specifically prohibits the termination of the employees' contract of employment under Section 6 or Section 7 of the Ordinance. There is simply no ambiguity there." Which rule of statutory interpretation was used? When should a court depart from such rule