Fascinating. I see that NARA is relying on a storage medium standard,
which at present doesn't include optical disks. Here's a relevant
paragraph...
The National Archives maintains permanent electronic records for
subsequent use by the original agency, other agencies, other
organizations, researchers, and the general public. NARA
generally satisfies such demands by providing copies of files.
Because of the multitude of computers and the variety of software
available to present and future researchers, NARA requires
agencies to transfer permanent computer files in a hardware and
software independent format. Specifically, files must be written
on half-inch magnetic tape, in EBCDIC or ASCII, without internal
control characters, on 7 or 9 track open-reel magnetic tape,
recorded at 800, 1600, or 6250 bytes per inch, or on 18 track
3480-class tape cartridge, recorded at 37,871 bytes per inch, and
blocked no higher than 32,760 bytes.