Section 2(53)(i) in New Town Kolkata Planning Area (Building) Rules, 2014
(i)"open space of a building" means an open space at ground level forming an integral part of the plot between the extreme face of the building and the nearest boundary line of the plot. Marginal open space along the entire front face or rear face or the side faces of the building shall be designated as front open space, rear open space and side open spaces respectively. For this purpose, the front of the building shall be that face of the building which faces the means of access of the building and the rear of a building shall be deemed to be that face of the building, which is the farthest from the means of access;