Among thousands of ISO standards, ISO (or more precise ECMA) has created the standard ISO 9960 for the CD format. The standard can be bought from https://www.iso.org/ or its identical version can be downloaded for free from
http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-119.pdf
For the 120mm DVD ISO/IEC 16448 or
http://www.ecma-international.org/publications/standards/Ecma-267.htm
For DVD-R, DVD-RAM, 80mm disk, see
http://www.ecma-international.org/publications/standards/Standard.htm
The iso9660 file system was originally very restrictive: 8 character filename, 3 character extension, capital letters. The iso9660 level 2 is less restrictive: 32 filename and level 3 allows fragmented files
The Rock Ridge is a iso9660 extension to support Unix permissions, user attributes, longer file names and Linux links. The Joilet extension is from Microsoft to extend iso9660 to have as example longer filenames.
Rock Ridge is embedded into the iso9660 file system, whereas Joilet is an additional file system on the CD next to the iso9660 file system.
The image will be mounted via loop device:
mount -o loop ~/knoppix/KNOPPIX_V5.3.1DVD-2008-03-26-EN.iso /mnt/loop
and can then be observed or verified with the burned DVD:
diff -qrd /media/KNOPPIX/ /mnt/loop/