Snooze

Hi can anyone tell me how to activate the 'Snooze' function under Alarm. I see how to set it up. Indeed it appears to be necessary to set it ON in order to set an alarm, however I have not discovered how to use it once an alarm goes off, i.e. no button on the handset and the manual appears silent on the subject.  Apologies if I am overlooking something obvious.
Thanks and regards Andym