__ssize_t, __off_t, __off64_t ?

[Marc Espie]

I'm trying to figure out what good those three defines are.
Up until now, OpenBSD didn't define these in an os_defines.h bit,
and it seems to work just fine.

Now, I've looked a little bit through the documentation, and I see
what I should define these too, but it doesn't appear to make any
difference...

I see that libio.h uses these, but my code seems to work just fine
without them... and so now I'm utterly confused.

Where do the defines come from if I don't add them myself ?

I've been looking through gcc 3.3 -> 4.1 sources, not noticing any
real difference there.

Please Cc me, as I don't follow the libstdc++ list assiduously...