How is genius info stored, and will editing a track's info change this? Does anybody know how songs hold genius info, and does changing a track name affect this?

Originally, I assumed each track had some sort of metadata which said how it should be turned into a genius playlist. This way, only songs with entries in gracenote would be able to make a genius playlist.

However, the other day, I bought an album, and when importing it into iTunes, fount it had no gracenote recognition. I added all the details (artist, track name, ect) manually.

A day or so later, I discovered that a couple of tracks could make a genius playlist, even when they weren't recognised on gracenote!

So now I assume that the data is held using the details that the track has (artist, genre ect.).

My problem is, if the data is stored by the details a track has, will changing the details remove the ability to create a genius playlist? I have many tracks where I have changed the details (ie. "Track" by "Artist feat. Artist" to "Track [feat. Artist]" by "Artist")

So does anybody know how this data is stored, and will it affect my genius playlists?
The song name, album name and length are used for recognition by Gracenote - which means when you changed and added the song details manually, it was recognised. 

As far as I know, the same details are used for Genius, so anything that Gracenote recognises will work - and the playlists are made on Apple servers.