For an optical recording medium having a phase change type recording layer on its a substrate and having as read only area and a writable area in a recording area, a data recording method is provided which records data in the writable area. This data recording method comprises a transfer step of transferring...http://www.google.com/patents/US20060182009?utm_source=gb-gplus-sharePatent US20060182009 - Optical recording medium, data recording method for rewritable-type phase change type optical disc, data erase method for rewritable compact disc, data erase method for rewritable phase change type recording medium, read only data erase method and recording/readout apparatus