> It also means that jmp_buf can be a structure, and the elements can
> actually be named.

Except that the current defn of jmp_buf is an array and
changing it to a struct will really screw things up thanks
to C semantics -- in ``setjmp(jmp_buf)'' you will pass
contents of the jmp_buf struct, not an address.  You can
insist on `setjmp(&jmp_buf)' but that makes it incompatible
with other systems.  I suppose

typedef struct { ... } jmp_buf[1];

will fix the `problem'.  Sigh....