I wrote:

> So, what are "a, b, c, d"?  In my SYSINTR file, at least, "b" and "d" are
> always zero.

Duh, I figured out a long time ago that "a" was the size (in bits) of the
return value.  I just forgot it.

But, "c" I haven't figured out.  Sometimes it's zero, sometimes it's one.