If the blocks you tried to explain are initialize, clear, and edit blocks (green, red, and blue), they are not entirely empty.
It is basically masked subsystems with callbacks; To check what callback each block has, do the following:
1. Right-click the subsystems.
2. Select "Block Properties"
3. select "callbacks" tab
In this case, each subsystem has a callback "OpenFcn" which will be executed when one tries to open the subsystems (double-click).