I would think you could identify the file system of the image. For example ISO1660, CDDA, CD Extra, UDF etc... Of course it's possible to have bootable CDs with hard drive images on them... they may have ISO extension, but in fact be FAT,hpfs,ntfs,ffs,bfs(quite common with BeOS 5 Live discs),hfs or hfs/iso(very common for discs written with a Classic Mac) or ext2fs images... this too should be identifiable, as the file system has as unique a property as a file. However, identifying such sub types is rather like identifying IFF files... an IFF file could be a sound, movie, picture, text, hypertext or anything else... Windows WAV files are IFF compliant, but so are AIFF Apple files, Quick Time Mov files and Amiga IFF/LBM files.
For me, this is where TrID becomes interesting... because LBM, ILBM or IFF would be valid extensions for an Amiga bitmap graphic... but, especially if the extension where IFF, that would still be valid for Quick Time MOV or QT file, an AIFF file, a IFF/SND file... but which is it? Just as an ISO could be a Audio CD image, a bootable Windows, Linux or BeOS image, a DVD/VideoCD/SVCD or many other things. Having definitions for the sub types is what is important.
As stated on Mark0 site, please classify what kind of ISO you are looking at, as though they were different versions of Word .DOC files.
