An optical information recording medium includes a plurality of rows of tracking tracks arranged at intervals, a plurality of recording portions provided between the tracking tracks and on which information is recorded by application of a light beam thereto, and an optically detectable mark provided...http://www.google.de/patents/US5038332?utm_source=gb-gplus-sharePatent US5038332 - Optical information recording medium including an optically detectable mark representing a boundary between the recording and non-recording areas
