From Just Solve the File Format Problem
CD-ROM XA (CD-ROM Extended Architecture; also spelled CD-ROM/XA) is a set of extensions to CD-ROM, ISO 9660, and other CD-related formats. It supports multipurpose and multi-session CDs. It was developed by Sony, Philips, and Microsoft. Among the formats based on it are CD-i, CD-Extra, Photo CD, and Video CD.
Regarding the ISO 9660 part, there is a "
CD-XA001" ASCII signature at offset 1024 of the volume descriptor. Each directory record has 14 bytes of "system use" data, and the bytes at offset 6-7 of that data are the signature "
- libcdio → libcdio-2.0.0.tar.bz2 → test/data/videocd.nrg
- Activision's Atari 2600 Classics → atari.iso