Let's be honest, the real 1999 design would have been a custom binary format that happens to use the endian of the system it was developed on, and leaks bits and pieces of unflushed memory buffers whenever it writes to disk.

No that would be an early 1990s file format ;)

1999 is exactly right for the start of the XML hype, everything had to be XML, it would single handedly solve the software crisis (after OOP failed to do that) because everything would be able to talk to everything!