Abstract: The bottom structure of small and medium size tank containers includes a pair of longitudinal fork lift channels and a pair of tranverse fork lift channels extending perpendicularly of the longitudinal channels. The transverse channels are defined by gaps between portions of profile bars forming the longitudinal channels. The profile bar portions are equipped with bottom plates which have openings for engagement by locking members provided on the loading platforms of vehicles. Locking plates are further provided at the bottoms of end frames of the tank container, each locking plate having a plurality of further openings for engagement by locking members as commonly provided on road and railway vehicles for ISO containers. A portion of an upper transverse bar of each end frame is formed as a grappler arm pocket provided with an upper guide plate. An upper portion of the guide plate forms an eye reinforced by a transverse member for engagement by a crane hook.