Optical disc, apparatus and method for recording and reproducing information, and apparatus and method for reproducing information

When an information recording and reproducing apparatus records pieces of user data (# 1 and # 2) on a write-once optical disk on which information can additionally be written, the information recording and reproducing apparatus performs a closing process so that the pieces of user data (# 1 and # 2) can also be reproduced with the reproduction-only apparatus. The closing process includes recording final recording position information NBM (A1) indicating an end position of the recorded information in the outside of the user data # 2. Then, in the case where user data # 3 is additionally written, the final recording position information NBM (A1) is erased using a predetermined pattern through the closing process, and