from http://bugs.musicbrainz.org/ticket/3464

I'm not quite sure, but of the few releases where there is also an apparently correct toc, several seem to be PS or PS2 game tocs:

http://musicbrainz.org/show/release/?releaseid=78395 http://musicbrainz.org/show/release/?releaseid=485761 http://musicbrainz.org/show/release/?releaseid=121426 http://musicbrainz.org/show/release/?releaseid=131230

also a few non-game trailing data track in toc ones I can't otherwise explain: http://musicbrainz.org/show/release/?releaseid=654803 http://musicbrainz.org/show/release/?releaseid=234730 and http://musicbrainz.org/show/release/?releaseid=654805