Multiple purposes
9.  Where any land or any building thereon is intended to be developed for 2 or more purposes falling within more than one Use Group, the development charge for written permission to develop the land for such purposes shall be determined in accordance with the Act and the formulae in rules 3 and 4 subject to the following modifications:
(a)where the land or any building thereon may be divided into parts each of which is intended to be used exclusively or predominantly for any one of those purposes, the Act and these Rules shall apply to each part as if each part was a separate development, and the development charge for written permission to develop the whole land shall be the aggregate of the development charge attributable to each of those parts;
(b)where it is impracticable to divide any floor of the building on any land in the manner described in paragraph (a), then, in determining the Development Ceiling properly attributable to such a floor, B2 in the formula specified in rule 4(1)(b) shall be the highest of the rates corresponding to both the appropriate geographical sector of that land and the various Use Groups within which the purposes of that floor fall;
(c)where any floor of any building on the land is intended to be used as service areas serving the various purposes for which the land is to be developed, then, in determining the Development Ceiling properly attributable to such a floor, B2 in the formula specified in rule 4(1)(b) shall be the average of the rates corresponding to both the appropriate geographical sector of the land and the various Use Groups within which such purposes fall.