Optical device and optical disc recording or reproducing method for optical disc including BCA having zone format identifier

An optical disc recording or reproducing method for recording or reproducing data on an optical disc, the optical disc that a track, where data is recorded in predetermined block units, is formed by wobbling at a spatial period in accordance with a radial position, and the track is divided into a plurality of zones in a radial direction, and that data is recorded, on the optical disc in each of the plurality of zones at a predetermined line density based on a ratio n/m (m and n are natural numbers) of a number of bits of a bit pattern of recording data to one wavelength of the wobbling, and

• the optical disc includes
• a first area having at least one of the plurality of zones,
• a second area having at least one of the plurality of zones different from the at least one of the plurality of zones in the first area, and a line density of fata different from a line density of data in the first area, and
• a Burst Cutting Area (BCA), where a zone format identifier specifying, for each of the plurality of zones, a zone table defining a boundary position of each of the plurality of zones and the ratio n/m of the number of bits is recorded, the optical disc recording or reproducing method comprising:
• acquiring the zone format identifier in the BCA on the optical disc;
• determining a recording or reproducing position in the at least one of the plurality of zones including a target position of data, based on the zone table corresponding to the zone format identifier;
• and
• recording or reproducing data from the recording or reproducing position.