The Categories in ADX are not layered since they can use REACT etc. to affect each other.

For the Cues for which two or more Categories are set, each Category volume is multiplied to affect the Cue.
For example, although the Category Groups are divided as main and sub, there is no parent-child relationship between these groups.
Since a Cue can belong to up to four categories (or a maximum of 16 if you changed the settings), you can divide the Categories into Category Groups forming a hierarchy.
The advantage of layering is that you can change the settings collectively at the top level, but this is also possible by specifying multiple Categories for each layer.