It's in 6.3, which says that you may only reference an object through
one of a list of types, and one is the character type.

There is not really any guarantee that you can usefully manipulate the
individual bytes, but I believe that's somewhere in the implementation
defined stuff.  Copies work.  Attempts to modify bits are subject to
strange behavior, but luckily, if we're looking at a known compiler
and CPU, we really don't care.

-s