Sets a timestamp marking the latest date and time that legacy data was recorded. This will usually be the moment that the application was converted from one system to the other but, if your application is configured to use a time-delay when logging data, then you may need to adjust the UseLegacyHistoryPriorTo value to account for the offset.
The time should be specified in the UTC timezone. For example, "2012-04-01 12:35:30.304", or the equivalent using a time stamp.
