Feature request: Intensional tagging

Note: I don’t know if “intensional tagging” is the proper word for the concept I want to convey.

So basically, I want a tag-like feature. But instead of defining the tag extensionally(by literally sticking that tag on each notes), I want it such that I could define the tag intensionally.

It works like this, intensional tag remembers search command you inputted to that tag, and then it retrieved the notes by invoking that search command.

I want this feature, because with this feature I could just simply save all my notes into one folder without any hierarchy and order whatsoever. I find that managing tags and notebooks are too much pain to handle.

I believe that other apps that have this feature tend to call them “Saved Searches”.