it has not yet been superseded). When combined with transaction time, this makes the table into a tritemporal table. The following is a list of real-world events that occurred between the United States presidential elections of 1964 and 1976: Suppose there is a constant 7-day delay between the decision time and the transaction time committed to the database. Then following the election of 1976 the database contents would be: President, Vice President, Valid From, Valid Till, Decision From, Decision To, Transaction From, Transaction To ---------------------------------------------------------------------------------------------------------------------------------- Administration(Lyndon Johnson, Hubert Humphrey, 20-Jan-1965, 20-Jan-1969, 3-Nov-1964, ∞, 10-Nov-1964, ∞) Administration( Richard Nixon, Spiro Agnew, 20-Jan-1969, 20-Jan-1973, 5-Nov-1968, ∞, 12-Nov-1968, ∞) Administration( Richard Nixon, Spiro Agnew, 20-Jan-1973, 20-Jan-1977, 7-Nov-1972, ∞, 14-Nov-1972, 17-Oct-1973) Administration( Richard Nixon, Spiro Agnew, 20-Jan-1973, 20-Jan-1977, 7-Nov-1972, 10-Oct-1973, 17-Oct-1973, ∞) Administration( Richard Nixon, Spiro Agnew, 20-Jan-1973, 10-Oct-1973, 10-Oct-1973, ∞, 17-Oct-1973, ∞) Administration( Richard Nixon, (Vacant), 10-Oct-1973, 20-Jan-1977, 10-Oct-1973, ∞, 17-Oct-1973, 13-Dec-1973) Administration( Richard Nixon, Gerald Ford, ∞, 20-Jan-1977, 12-Oct-1973, ∞, 19-Oct-1973, 13-Dec-1973) Administration( Richard Nixon, (Vacant), 10-Oct-1973, 20-Jan-1977, 10-Oct-1973, 6-Dec-1973, 13-Dec-1973, ∞) Administration( Richard Nixon, (Vacant), 10-Oct-1973, 6-Dec-1973, 6-Dec-1973, ∞, 13-Dec-1973, ∞) Administration( Richard Nixon, Gerald Ford, ∞, 20-Jan-1977, 12-Oct-1973, 6-Dec-1973, 13-Dec-1973, ∞) Administration( Richard Nixon, Gerald Ford, 6-Dec-1973, 20-Jan-1977, 6-Dec-1973, ∞, 13-Dec-1973, 15-Aug-1974) Administration( Richard Nixon, Gerald Ford, 6-Dec-1973, 20-Jan-1977, 6-Dec-1973, 8-Aug-1974, 15-Aug-1974, ∞) Administration( Richard Nixon, Gerald Ford, 6-Dec-1973, 9-Aug-1974, 8-Aug-1974, ∞, 15-Aug-1974, ∞) Administration( Gerald Ford, (Vacant), 9-Aug-1974, 20-Jan-1977, 8-Aug-1974, ∞, 15-Aug-1974, 26-Dec-1974) Administration( Gerald Ford, Nelson Rockefeller, ∞, 20-Jan-1977, 20-Aug-1974, ∞, 27-Aug-1974, 26-Dec-1974) Administration( Gerald Ford, (Vacant), 9-Aug-1974, 20-Jan-1977, 8-Aug-1974, 19-Dec-1974, 26-Dec-1974, ∞) Administration( Gerald Ford, (Vacant), 9-Aug-1974, 19-Dec-1974, 19-Dec-1974, ∞, 26-Dec-1974, ∞) Administration( Gerald Ford, Nelson Rockefeller, ∞, 20-Jan-1977, 20-Aug-1974, 19-Dec-1974, 26-Dec-1974, ∞) Administration( Gerald Ford, Nelson Rockefeller, 19-Dec-1974, 20-Jan-1977, 19-Dec-1974, ∞, 26-Dec-1974, ∞) Administration( Jimmy Carter, Walter Mondale, 20-Jan-1977, 20-Jan-1981, 2-Nov-1976, ∞, 9-Nov-1976, ∞) Consider the question of who would be president and vice president for a valid time of 1-Jan-1977: Nixon/Agnew when using a decision time and transaction time of 14-Nov-1972 Nixon/(Vacant) when using a decision time and transaction time of 17-Oct-1973 Nixon/Ford when using a decision time and transaction time of 8-Aug-1974 Ford/(Vacant) when using a decision time of 8-Aug-1974 and transaction time of current Ford/Rockefeller when using a decision time and transaction time of current Bitemporal Modelling A bitemporal model contains both valid and transaction time. This provides both historical and rollback information. Historical information (e.g.: "Where did John live in 1992?") is