It seems that there are two different versions (at least) of io-net.h
Installing QNX RTP 6.1 provides one version, dated May 7 (2001), 9175 bytes
Installing the network ddk provides another, dated Dec 21 2000, 9040 bytes
The latter has, among other things _REG_INIT_ONCE defined, whereas the
Is there a method behind this madness? What does QNX recommend for
developing a network filter under 6.1? What other ‘gotchas’ await?