Maybe, yes. There are certainly worse offenders than ELF, but I still don't see how it satisfies 3 out of the 4 MUSTs. There is no byte with the high bit set a

Maybe, yes. There are certainly worse offenders than ELF, but I still don't see how it satisfies 3 out of the 4 MUSTs. There is no byte with the high bit set and it is a valid ASCII sequence and therefore also valid UTF-8. When it comes to the "eight is better" requirement, at least Linux does not care what comes after the fourth byte for identification purposes, so I think that does not count either.