Whats a multisession disc?
A session is a recorded segment that may contain one or more tracks of any type. The CD recorder doesn’t have to write the entire session at once, but the last session on a disc must be “closed” before a standard audio CD or CD-ROM player will recognize it. Additional sessions can be added until the *disc* is closed or there’s no space left. Multisession writing was first used on PhotoCD discs, to allow additional pictures to be appended. Today it’s most often used with “linked” multisession discs, and occasionally for CD-Extra discs. These require a bit more explanation. When you put a data CD into your CD-ROM drive, the OS finds the last session on the disc and reads the directory from it. (Well, that’s how it’s supposed to work. Depending on your operating system and CD-ROM drive, you may get different results.) If the CD is ISO-9660 format – which it almost certainly is unless it’s a Macintosh CD written in HFS – the directory entries can point at any file on the CD, no matter whic
