Rule 11 which fixes the order of priorities in allotment of residential buildings states in sub rule (1) that: "In making allotment of a residential building, .the following order of priorities shall be observed: Firstly, for public purposes; Secondly, for accommodating a person against whom an order has been passed for eviction under Section 21, not being a tenant referred to in Explanation (1) to Section 21(1), or a decree has been passed in a suit filed with the permission of the District Magistrate under section 3 of the old Act (or such suit or application is pending) and who or 131 members of whose family do not own or hold as tenants any other residential building in the same city, municipality, town 'area or notified area; Thirdly, for accommodating others; and in each of the above categories subject to the provisions of sub rule (2), the principle "first come, first served" shall be followed.