Fuente: WIPO "tomato" There is described a method for applying opening devices (2) at predetermined areas (3) of a web (4) of packaging material including a plurality of web portions (4a), the method comprising the steps of feeding the web (4) through an application station (6) by feeding one web portion (4a) at a time through the application station (6), detecting the position along the advancing path (P) of a first predetermined area (3a) first entering the application station (6) and the position of a second predetermined area (3b) last entering the application station for a respective web portion (4a), calculating a calculated distance (D1) between such detected positions, calculating a distance offset value (E) as a function of the difference between said calculated distance (D1) and a nominal distance (D2), controlling the position of said respective web portion (4a) at the application station (6) as a function of the calculated distance offset value (E) by arranging one first predetermined area (3) at a distance equal to a fraction (E/k) of said distance offset value (E) from a reference position of said one predetermined area (3).