Mathematica Tutorial: Notebooks And Documents - Wolfram Research

24 Notebooks and DocumentsThe time information is saved in each cell of the notebook, in the form of a list of numbersand/or pairs of numbers.Cell[BoxData["123"], "Input",CellChangeTimes->{{3363263352.09502, 3363263354.03695}, 3363263406.22268,3363263441.939}]Each number represents the exact time of an edit, in absolute time units. A list of pairs indicatesmultiple edits that have occurred during this interval.Consecutive edits are recorded as an interval if they happen within a set time period. Thisperiod is determined by CellChangeTimesMergeInterval, which can be set through the OptionInspector or the Advanced section of the Preferences dialog. The default is 30 seconds.The notebook history tracking feature can be turned off at the global level by using the Preferencesdialog or by setting TrackCellChangeTimes to False.