michelvanputten (2017/4/23: 5:51:12) - I would annotate this as separate events. This is most likely a patient with a childhood absence epilepsy, and the 3 Hz SW discharges often occur in paroxysms of various duration, ranging from a few seconds to longer. 

Mark Quigg (2017/4/24: 9:40:57) - Two separate seizures. In counting absence seizures on prolonged recordings, we typically specify a "minimum" duration - on a 30 second page we'll use a 3s minimum - and count those that meet that criteria as well as giving an estimate of average duration. We will also state qualitatively the persistence of those discharges under the criteria.