Unique id of a process (not pid)

[cronfy]

Hello,

Is there any unique identifier of a process in FreeBSD (not PID)?

I am trying to get list of processes and watch for changes
with kvm_getprocs(). I want to catch every process start and exit (except
those processes that were started and finished between calls to
kvm_getprocs()).

But between calls to this function one process may exit and be replaced with
another process with the same pid and same command name. The only difference
is a start time of processes. Looks like this is a solution, but process
start time may change if system time was shifted (i. e. with ntpdate). I can
track these shifts too, but it looks to be too complex.

Is there any simpler way to identify a process? Thanks in advance.

-- 
// cronfy