PURGE_DATE is an optional date field, used by the UMHP - History purge program for controlling data retention.
The Administrator may specify a specific date in which all historical data prior to this date will be purged. Purge Date will take precedence IF all three fields are filled in. Thus if you have it set to normally delete rows that are older then 5 years BUT for a special run want to delete all rows prior to a specific date, you can.
