妥当な日付か時刻の文字列

History

Time	Change
2008-12-13 03:48:39+00:00	Created
2008-12-13 03:48:39+00:00	Associated with 8458
2014-05-06 10:57:27+00:00	Disassociated from 8458
2014-05-06 10:57:34+00:00	Associated with 21797