For example, a "Soft" playlist contains all tunes that are both warm and restful; the "Well Awake" playlist contains tunes which are not restful, and not too violent; "Pop" playlist contains tunes which are popular but not too much main-stream; "Pop++" contains only (assumed) mainstream popular tunes, etc. I'm happy with a system of tagging which works quite well after months of usage. Read the rest if you'd like to see it.
For each dimension, I give a note to each tune, within "irrelevant," "not at all," "yes," and "yeah, definitely." Those four steps seems to be enough. And more steps would make smart play list hard to design. For example, let's take violence. I add in the comment (the grouping field may be preferred) of each tune "Violence-," "Violence=," or "Violence+," depending on its violence. Violence- means calm, Violence= means violent, and Violence+ means ultra violent (God knowns that some songs are). If a song is not tagged Violence, it is considered not violent, and not calm, let's say, normal. Here are examples, on a few tunes that many of you may know:
- Miles Davis - Flamenco Sketches : Modern=, Pop=, Rest=, Violence-, Warm+
- Louis Prima - Just A Gigilo / I Ain't Got Nobody : Modern-, Pop+, Warm=
- JS Bach - Goldberg Variations : Modern-, Pop=, Rest+, Violence-, Warm+
- The Beatles - Sgt Peppers - A day in the life : Modern=, Pop=, Trip=
- Deep Purple - Speed Kind : Modern=, Pop=, Violence=
- Massive Attack - Protection : Warm-, Modern=, Pop+, Trip=
- Einsturzende Neubauten - Negative Nein : Modern=, Pop-, Rest-, Trip=, Violence+, Warm-
- Something violent but not too much? Comment contains "Violence=".
- Something violent, even very violent? Comment contains "Violence" but not "Violence-".
- Something which is not violent? Comment doesn't contain "Violence=" nor "Violence+".
- Something which is not violent and not calm? Comment doesn't contain "Violence".
- Melancolic: any genre, tune is Warm-, not Violence+, not Violence=, not Rest-
- Good mood: any genre, tune is Warm+, not Rest+, not Violence+, not Pop-
- Soft: any genre, Warm but not Warm-, Rest but not Rest-
- Pop: genre is not jazz, not classical, tune is Pop, but not Pop-, Modern but not Modern-, not Trip+, not Rest, not Violence-, not Warm-.
- Junkie: genre is not classical, tune is Trip but not Trip-, not Violence+, not Rest-
- Not archived on CD: tune is Archive-
Anyway, now my iPod is my favourite companion within the non-humans -- it never fails giving me what I want to hear. This is completely new to me -- like, er, I live in the XXI century?

