The game disc is also mentioned here
http://www.asahi-net.or.jp/~ev5k-itu...gaku/Toku2.htm but I don't know if it omits any data track.
I think this might be out of scope if the music serves the main purpose of being played within the game and is just a means of storing audio on the game disc.
IMO this makes it different from special contents discs where music files are stored as a bonus for listening outside of the games. Add to that the scan which advertises this only as a "game disc".
Somewhat similiar could be BGM / music discs that contain ONLY music and if inserted, upgrade game music from low quality to CD audio. Some of these entries we have in the database.
It's not the place to start a discussion on scope but it would be interesting to find out exactly how and for what purpose the music is stored on the game disc and classified as "soundtrack" and not just game audio files.