What exactly ntp compliant means ? . If i have only ntpdate , can i say i am
ntp compliant ..or i have to run both server and client ?

Thanks,

As far as I know, it means nothing.

Now there are certain standards called "RFC" which prescribe the
algorithms and functions of ntpd, and associated software.  I believe
that RFC-1305 is the RFC that governs NTP V3.  An RFC for V4 is being
developed but is not yet ready for publication.

If you need to have the correct time at all times, you need to run ntpd
or some similar software.  Just running ntpd is not, by itself,
sufficient.  You must write a configuration file that tells ntpd what
servers or hardware reference clocks to use.  This requires a little
understanding.  Blindly copying someone else's configuration file may,
or may not, work for you.

Running ntpdate will get and set the correct time but you cannot run it
once and forget about it.  Your computer's clock will drift a few
seconds each day; it might gain or lose two or three minutes per month.

Ntpd will discipline the clock, requiring it to run at exactly one
second per second and will bring it into synchronization with the
correct time and keep it in synchronization.

A lot of NTP documentation can be found at http://www.ntp.org

That's really a question for your contract lawyers.  We are better at
answering whether a sufficiently well described system will meet
specified technical criteria.

However, I would suggest that ntpdate was only SNTP compliant, not
because it doesn't support acting as a server, but because it doesn't
implement  the client protocol and client internal processing fully.

Generally, we would say that there are very few real life cases were
there are significant obstacles to installing ntpd, but ntpdate could be
used.