What does factory reset in service menu do ?

The question is: What does factory reset in service menu do l!!!!????

Made myself a factory reset ( stupid ! ) in service menu (Samsung LE40A856). I did not made any other changes myself in service menu!
Know i don't know what has changed.
Only know that the number of hours that the tv had played is set to 0.
The picture of the TV seems also the same as for the reset.
Then I have made some values changed in service menu (and this time, however, written down! ) and made the factory reset again.
And what proves to be, the values have not changed.
This would mean that factory reset not reset to factory values?
But what does it do than???
Someone who can say about this something sensible?
Moreover I have a service guide in which is indicated at some options in service menu the dates/values.
But i think this can not be the "right"values since each TV (also from same serial) has is own calibration. Or i'm i wrong?
If I look for example to "calibration adjust" in service menu then the values/dates are compleet differently as here in the service guide. I alsso cannot change the values in "calibration adjust"? someone that can verify once??

Greeting,

Trima