@RichiH #ArchiveTeam tries to keep some info at https://wiki.archiveteam.org/index.php/Rescuing_optical_media and http://fileformats.archiveteam.org/wiki/Sources ; LOC has some more https://www.loc.gov/preservation/care/record . Not much info there about m-disc except passing mentions https://www.digitalpreservation.gov/meetings/DSA2017/Day_2/05_AM_Kransky_5D_Optical_Storage.pdf , so it's not something you can rely on for the long term.