no 3 634 993 pasco and wolfelsperger u k pat no 1 445 285 du pont u s pat no 3 260 032 hill et al or in modern packaging may 1971 at pages 60 to 62 fig4 shows one form of means for opening and closing the chamber 19 20 namely a fluid pressure operated jack 23 programmed to operate in a repetitive cycle coordinated with operation of the feed means 25 for the support sheet 10 and the cover film 15 so that the film advancing movement occurs while the chamber is open and the film advance is interrupted as the chamber closes a suitable vacuum source is connected to the duct 24 for evacuating the space between the support sheet 10 and the cover film 15 the evacuation operation being coordinated by means of a central programmer with the operation of the chamber opening and closing means in a programme which is well known to the expert in this art although the above description relates to the simultaneous packaging of a set of articles 11 12 13 and 14 in a rectangular array extending laterally across a continuous web any convenient number of such articles even including only one article may be packaged during each operating phase of the vacuum chamber 19 20 defining the sealing station upon completion of the sealing operation the package will have the configuration shown in fig4 in that the raised 34 dummy product 34 defining ribs 17 will remain in the support sheet 10 and the 34 webbing 34 18 not shown in fig4.