Currently Features is discarded (raticular it don't support in WEB) and R&D reccomend use Overflow tables if we need have some specific attributs.
But it is not optimal way, often there are some type of assets that have a few specific attributes, for example, different tipe of VM have different properties for CPU. Create different tables for each VM type is not good idea, create different attributes for every VM type is not good idea too, because it make structure of data very complex.
In other case we have little numbers of assets, that have specific attributes, for example, we have only two phone stations, that want manage in AM too and they have some set specific attributes. To create new Overflow tables for every such assets it is wery complex way.
So, in my poin of view, it would be great to have ability to create specific attributs that will be applied for different assets according a set of rules.