Categories in Deepser are organized in a hierarchical tree structure of up to 3 levels.
So each first level category corresponds to zero or more second-level categories, and for each 2-level category zero or more third-level categories correspond.
This structure is called hierarchical because if you apply visibility restrictions on a higher-level category, the lower-level categories will inherit those limitations.
Categories in addition can be made visible for all models, by default, or only for a specific model.
