Method for playing back information recording medium

A method for playing back an information recording medium, said information recording medium comprising:

• a first region in which type identification information for identifying a type of the information recording medium is recorded by recesses and/or protrusions which are formed by a given modulation method and whose lengths are longer than a length of an optical system resolution limit of a playback device;
• and
• a second region in which content data is recorded by recesses and/or protrusions which are formed by the given modulation method and which include a recess and/or a protrusion whose length is shorter than the length of the optical system resolution limit,
• the first region containing first address information recorded therein in a first address data format,
• the second region containing second address information recorded therein in a second address data format that differs from the first address data format, and
• the given modulation method being a 1-7PP (Parity Preserve/Prohibit RMTR (Repeated Minimum Translation Run Length)) modulation recording method,
• said method comprising:
• irradiating the first region with playback light having normal medium playback power to read out the first address information from the first region;
• decoding the first address information with use of a first decoding process circuit of the playback device;
• playing back the type identification information recorded in a predetermined address of the first region;
• determining playback setting of the second region based on type identification information;
• irradiating the second region with playback light having playback power corresponding to the playback setting of the second region to read out the second address information from the second region;
• decoding the second address information with use of a second decoding process circuit of the playback device, the second decoding process circuit being different from the first decoding process circuit;
• and
• playing back the content data recorded in a predetermined address of the second region.