half and half
Found it:
"Our Langstroth hive has a number of unique features, including the hard plastic edges which double as frame runners and provide protection against the hive tool. The hive bodies also interlock with a raised portion on the top of each hive body engaging with a corresponding “socket” on the underside of the upper hive body. This design is coupled with another unique feature – these hives are neither top or bottom bees space, they are a bit of both. This feature is linked to the hive body design and shows up when the bodies are replaced after an inspection. With a conventional hive it is usually recommended to replace the hive body at a large angle to the one below and then rotate it round into correct alignment. With our hives the upper body or super should be replaced at a slight angle only. Smoke is then applied around the joint to chase away any bees and then the body is rotated round the last few degrees when it will drop down into place, with the beekeeping taking some of the weight to minimize any jarring, which will excite the bees. This means the final movement between the bodies is vertical not horizontal and why the idea of top or bottom bee space does not apply. The bee space is between the frames, with the upper frame dropping downwards onto the lower one."