What do you mean by the main shelf and the shelf?
The actual difference between the main frame and the rack is only a vertical column, and the other configurations are the same.
There is a distinction between the main frame and the rack. Straightforward, each row of shelves has only one main frame, and the others are racks. That is, a row of shelves is made up of 5 shelves, and then 1 main frames and 4 racks.
The shelves are lined together with multiple shelves, and when the shelves are connected, the columns between the first shelf and the second shelves are shared
