How is clock graph in "trends" column generated

Hello Xymon Gurus!

I have searched the interwebs for it but could not find anything useful.

My question is how are the values calculated for the Clock offset graph,
displayed at the bottom of the "Trends" column. I have seen some posts (and
my experience also confirms this) that Xymon's ntp check (specified in the
hosts.cfg) is only to see if NTP daemon on a client is up (responsive).
While the clock offset is plotted via some internal logic (client feeds
data to the server).

Would really appreciate if some one can throw some light on it!

Some links that I have gone through:
http://osdir.com/ml/monitoring.hobbit/2007-03/msg00361.html
http://lists.xymon.com/oldarchive/2009/01/msg00417.html


-- 
Regards,
Junaid Shahid,
TODO:______