With append_only_flag reset to 0, data is recorded over existing data on a disc in accordance with the value of volume_write_protect_level. With append_only_flag set to 1, on the other hand, data can not be recorded over existing data on the disc but can be appended to already recorded data in a range defined by the value of volume_write_protect_level. As a result, it is possible to prevent new data from being written over already recorded data by mistake and to utilize the recording area of the disc efficiently.