It was thus said that the Great Vintage Computer Festival once stated:
HOWEVER, this makes it very difficult to use the imagefile on an emulator.
To use the floppy disk example again, if the emulator wants Track 14
Sector 8 (or Block 417) but it has not been explicitly laid out in the
imagefile because it was originally zeroes, then the emulator, if poorly
designed, may crap out.
Are you trying to create an archive format, or a format that is to be used
by emulators? I say skip the emulators and concentrate on archival
purposes. An emulator can then use the archive format to create a disk
image in whatever internal format it requires.
Don't complicate the problem.
-spc (And don't try to become everything for everybody ... )