Gent Vigilon...
This for example can be used for investigtion time.
I.e. If a single detector is activated it may start a timer before the sounders are activated. The Acknowledge button could be pressed within this set time to extend this time for a further period of time for investigation prior to the alarms being activated.
Good example of functions 
Yep good example but isn't this completely not what you're talking about ??
A button by what ever name that allows you to start a timer to extend a search period is not an aknowledgment button that is going to force the user into inputting a reason into the log as to why the system went off.
Sorry Dave if you are not getting the point!
All what I was looking for is ‘acknowledgement button’ as third button other than silence and reset ones, it doesn't matter what function is been programmed to do, since it can be programmed to do what we want it to do, among those functions are the good example of Big_Fella, other function what I have stated previously, programming (alarm classifications). And yes it is not required by either BS or manufacturers or any one else it's rather just new idea... etc you may find out your own way to deal with false alarms reduction dilemma and there is nothing wrong with that, as long as you are acting to reducing them.
