FYI: 64-bit IFF in the wild: DSDIFF

[sh1boot]

Philips went ahead with a 64-bit IFF derivative with their DSDIFF format. I'm not sure if this is one case of wider use of this format, or if it's only ever used for DSD.

Identified with a FRM8 tag, and they kept the 16-bit padding.

Personally, I'd have padded to four bytes, because that makes the chunk IDs all appear at chunk-ID-sized alignment, which looks nice in hex dumps.