There needs to be space available next to the doorway equal to the width of the doorway for a single basic sliding door to slide into when opening the door. Bypassing sliding doors on multiple sliding tracks can be installed within the doorway, in which case they do not need additional space next to the doorway. This makes it possible to open the doorway enough by sliding the sliding doors next to each other on one side of the doorway. As a rule of thumb, the depth of a sliding door is the depth of the track system but, with regard to ceiling fixing, for instance, the door can be thicker than the depth of the track system, in which case the thickness of the door determines the required depth.