Abstract: A container structure including a bag body formed of flexible plastic film with a top through which the contents may be filled or emptied from the bag interior and a mechanically interconnectable rib and groove fastener along the top which is unopenable manually externally such as by having an absence of flaps or projections at the top. In one form the top of the bag has to be torn off along predisposed paths to remove the interlocked rib and groove element, and in another form, the walls have to be cut at an appropriate location so that they may be pulled apart.