Tags with a hierarchy

[Perspective]

I would like a functionality that allows tags to be structured hierarchically.

Each tag can have one or more parent tags. In this way, any number of parallel hierarchies of tags can be created.

Example of a tag hierarchy:
- Customers
-- Customer A
--- Project 1
---- Subproject 1.1
---- Subproject 1.2
--- Project 2
---- Subproject 2.1
---- Subproject 2.2
--- Project x
-- Client B
--- Project 3
---- Subproject 3.1
---- Subproject 3.2

Now files are given tags.

I can now search for the tag ‘Subproject 2.1’ and find all files with this tag. This works now.
I can also search for the tag ‘Project 2’ and find all files with this tag. This also works now.
I can now search for the tag ‘Project 2’ including hierarchy and find all files with the tags ‘Project 2’, ‘Subproject 2.1’ and ‘Subproject 2.2’.
If I search for the tag ‘customer’ incl. hierarchy, I find all the files that have a tag in this tag hierarchy.

[admin]

This is not planned as you wish, but you can easily achieve the same functionality by clever naming of the tags:

Instead of hierarchy...
--- Project 1
---- Subproject 1.1
---- Subproject 1.2

... do this:
--- P1
--- P1.1
--- P1.2

and search for "P1*" to find all P1, P1.1, and P1.2.