Point. They are, however, nowhere near as robust as the ROM of old, and are often not truly ROM at all, so I wasn't really thinking of them in that category. Technically, you are correct, though.

The same can be said of the written English language (or just language in general). I expect, that with time and patience, it would be perfectly possible to reconstruct the system needed to read a data format, just from the data format itself. Harder, certainly, with more layers of encoding, but by degree, not kind.

If we are attempting to preserve data beyond the point where the human race can look after it themselves, chances are that any information at all, regardless of storage medium, will require a fair bit of detective work, decryption, and translation.