(a) prescribed commercial premises comprising or forming part of an existing building that was constructed on or before 2 May 1997 as well as to premises comprising or forming part of an existing building that is constructed after that date;
(b) any specified commercial building listed in Schedule 4.
(2) The fact that the requirements of this Ordinance relating to specified commercial buildings apply to any particular commercial building shall not be regarded as having the effect of disapplying the requirements of this Ordinance or of any other enactment, not relating to specified commercial buildings, from that particular commercial building.
(3) The fact that part of any particular commercial building falls within the meaning assigned to prescribed commercial premises in section 3 shall not be regarded as having the effect of disapplying the requirements of any other sections of this Ordinance from that part.