Under section 3 the Land Commission may impose an obligation on allottees of holding and parcels to reside thereon (sect. 2). An agreement or undertaking to purchase a holding or parcel of land from the Land Commission may contain provisions whereby the purchaser agrees not to sublet or part with possession of the holding or parcel or any part thereof until the holding or parcel is vested in him, or that prohibit the purchaserto make, on or after the operative date and before the holding or parc