[nikoski]

Thanks!

Sure, i see. Basically tags could apply to anything and are a sort of incoherent or "mixed bag" of different meanings, whereas by a column you can achieve a more specified idea already at the highest level of the hierarchy.

But to achieve a clean hierarchy within the category "Tags", separeted from the "mixed bag" of the rest of the tags, wouldn't it be similar (to a column) to create a tag called "MyTags." and create a hierarchy inside it?
I mean: instead of creating a column called "genre" i could create a tag called "-!MyTags_Genre." (to put it no top alphabetically) and tag all the items inside it the same way as in a column "genre".

Wouldn't it only "shift" the hierarchy simply 1 level deeper when compared to the same sort of hierarchy based on a column "genre"?

Or is there any "technical" point to prefer a column vs. tag for a hierarchy in terms of general usability in calibre like searching, finding, viewing the items ..., anything (except the specified meaning) essential that you get using a column, which is not possible with tags?