NONBLOCK should generally be used.  NDELAY is older, stranger, and not POSIX.
I found references to NDELAY in the slattach program as well.
I'd go ahead and remove the NDELAY thing, too :)

Does everybody use PPP now, or are there others (like me) still struggling
with SLIP?  Contact me if you are interested in auto-reconnect scripts.
-- 
VaX#n8 (vak-sa-nate) - n, CS senior++ and Unix junkie - vax@ccwf.cc.utexas.edu
Just the vax-man.  Read my MIPS, no new VAXes!        - PGP key on request