Fuente: WIPO "tomato" A multilayer sheet of packaging material for producing a sealed package of a pourable food product comprises: at least one base layer for imparting stiffness; a plurality of lamination layers applied to and covering both sides of the base layer; a pre-laminated opening which is formed by a through slot provided in the base layer and is covered by one or more of the lamination layers, the pre-laminated opening being configured to receive an opening device for outpouring the pourable food product; a plurality of folding lines configured to define an edge between two adjacent walls of a sealed package, wherein the pre-laminated opening is not intersected by any one of the folding lines and includes an outer rim being arc-shaped so as to define a first portion of a first circumference.