> When developing software for NetBSD, what should we do so that it remains
> compatible between the last release and -current ?

<sys/param.h>'s "NetBSD" definition, "NetBSD1_0" definition, etc.

> In particular, a few header files have changed/been removed (namely in
> /usr/include/sys) but these changes don't appear on the other 'BSD ports.

umm, it's not clear to me how this is really relevant, if what you're
trying to do is determine the NetBSD version...  I.e. if you know it's
NetBSD, then you _should_ be looking for NetBSD-specific clues...

but because of the definitions mentioned above, this kind of thing is
unnecessary.

> There is a __NetBSD__, but what else is available to us ?

"see above."  8-)


cgd