Tags (keywords) metadata used as in Adobe Bridge

In looking for a file manager able also to read/write metadata ebooks (pdf, epub, etc.) I found DO as the one among the many.
In v.10 that I tested, I saw the support also for XMP format metadata and its own panel metadata, which was a perfect addition.

To organize many ebooks I use keywords, and I noticed that in DO they are called Tags. Now an image organizer like Adobe Bridge makes and effective use of the keyword (or Tag) metadata showing it as a tree structure, very similar to outliner list. This image helps showing its implementation:
http://jessicalanan.com/wp-content/uploads/2013/12/Adobe-Bridge-Keywords2.jpg

In such an implementation I see three advantages:

  1. The user builds the keyword structure and than uses the same keywords (Tags) repetedly and consistently with his/her files.
  2. The structure is hierarchical and so some keywords appear more general than others. This is very good for organizing Tags and for assigning them to the files.
  3. The keyword structure is used to assign the metadata to the files but also as a easy-immediate filter to navigate and restrict a selection of files.

It would be great if DO could emulate something similar.
Thanks for your excellent file manager and for listening.