Link Disc is a feature of DMP2/BS/CE*
if you insert in DMP2 a DMP1 disc, you'll get some new chars and equip while playing DMP1-Songs
if you instert in BS a CE disc, you'll get also new chars, songs(!) and equip while playing CE-Songs. You can also insert DMP1/2 discs to unlock chars, but unfortunatly you can't play songs on them
*=CE lets you only unlock some chars/equip (and songs? I dont know anymore) |