What is the purpose of the the parent category field on a model category?

[CMDB Whisperer]

In recent versions of ServiceNow, they have introduced the Parent Category field on the Model Category table, but is unclear to me what the intended use of this is, both how it's supposed to be used and why it was added.

At face value, I could interpret this field in two different ways:

1) The parent category is the category whose CI class is an ancestor of the CI class of the child category.

For example, the parent CI class of cmdb_ci_server is cmdb_ci_computer, and therefore the parent category of Server would be Computer.  Not sure what the purpose of that would be.  Is this for categories that are tracked as assets but not CIs, so you can still provide a type-based hierarchy?  Or in case your CI class hierarchy is deeper than your category hierarchy and you might want to skip a level?

2) The parent category is the category that is expected to be used by the parent asset.

For example, if a hardware asset of category Blade Server is expected to have a parent hardware asset of type Blade Chassis, and therefore the parent category of Blade Server is Blade Chassis?  I could see why this might be useful, but I can't find any functionality that is tied to this.  

If I had to guess, it would be option 1.  But in either case I could not find anything to indicate how this is specifically supposed to be used and I'm not sure if there is any value in updating the existing model categories to have parent categories.

[Mike Condon]

I believe the concept is to group similar fields together. Server is a subset of computer, as many of the server fields belong to all computers (IE: Installed RAM, CPU, Serial Number, etc).  However, any fields that specific to servers will be in the Server Class. 

[CMDB Whisperer]

I'm not sure how Model Categories would have anything to do with CI schema.  Server already extends Computer so the additional fields in the Server class is self-evident without Model Category.

[Martin Noack]

I have the same question. The official documentation page does not even mention this field:

https://docs.servicenow.com/bundle/paris-it-service-management/page/product/product-catalog/task/t_CreatingModelCategories.html

[CMDB Whisperer]

On a related but separate note, the Product Model Class doesn't seem to have any effect either.  Although I appreciate that it exists it doesn't seem to be enforced or used in any way.  I would think that it would be used when creating models on the fly from a CI creation, e.g. when using Discovery, but this doesn't appear to be the case.