A disk-shaped recording medium has a groove only one of whose side-walls wobbles or deviates in radial directions of the disk in order to prerecord first address information. In addition, the disk medium has block areas in the groove and in the land where the first address information is given and sector...http://www.google.com.tw/patents/US5870375?utm_source=gb-gplus-share專利 US5870375 - Disk-shaped recording medium with a groove section having a wobbling side wall
