Limitations to .iso format?

I am creating disc images of my cd’s and dvd’s using Alcohol software. For both CD and DVD I have the option to use Alcohol’s format (mdf) or the universal iso format. I prefer universal formats in general, but are there any restrictions on the iso format such as not being able to back up certain types of discs? or will the resulting .iso image always be identical to any .mdf image i would create? Also, is .iso compatible with Blu-Ray backups. I haven’t had the chance to see if this is an option yet.

Thanks for the help.

.iso format is more or less useless for working back-up copies of virtually all copy protected discs.

ISO format only supports single-session data discs - e.g. multi-session discs and Audio CDs are not supported.

ok, so is the mdf a good choice for backing up every type of disc? is there one that is brand-neutral? (mdf is alcohol, iso is generic)