Ganz einfach, alle Interfaceklassen sind gleichberechtigt, werden gleich behandelt, man kann beliebig viele Interfaces pro Klasse haben.
... although with the editor you can only hide interfaces by class. With Lua you can show hide interfaces by interface name. By the way, there is no difference between the classes. They do not endow the interface with different options or anything, they are more like a group, in which you can assign interfaces to. It's actually possible to create custom classes via the explorer tool or by manually opening up the your ved file in an external text editor like sublime text, atom or notepad++ & writing the new classes to section containing the classes - I don't recommend using the latter method though as it's easy to mess up your ved by accident - it only takes one typo or an accidental click of the delete key etc.