Most of the time when trussing a process you are not interested in all the system calls that are working perfectly and which are scrolling by in high speed. However you are very interested in those yielding an error. With truss -N you can now shorten the truss outputs significantly by showing only syscalls returning with an error.
I think most of you know the problem of seeing the few failing syscalls when a large number of them are passing by during the truss. The new option shortens output significantly.
root@solaris:/lib/svc/method# truss -N cat /etc/narf
openat(AT_FDCWD, "/var/ld/64/ld.config", O_RDONLY) Err#2 ENOENT
openat(AT_FDCWD, "/etc/narf", O_RDONLY) Err#2 ENOENT
cat: cannot open /etc/narf: No such file or directory
root@solaris:/lib/svc/method#