Information recording medium and playback device

An 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,
• the information recording medium further comprising a blank region between the first region and the second region, the blank region (i) including a portion in which the first address data format is switched to the second address data format and (ii) including address information and no significant information other than the address information,
• the second region having a track pitch shorter than a track pitch of the first region,
• the blank region having a track pitch which is, at a boundary between the blank region and the second region, equal to a trach pitch of the second region, and
• the given modulation method being a 1-7PP (Parity Preserve/Prohibit RMTR (Repeated Minimum Translation Run Length)) modulation recording method.