The IDENTITY keyword is used to modify a column name, and is used to specify surrogate keys. The first number parameter after IDENTITY specifies the starting value for the surrogate key, and the second number specifies the increment value for each additional record. Thus a column named RelationID and modified by IDENTITY (4000, 5) will be a surrogate key named RelationID with an initial value of 4000 (for the first record in the relation), and with following values incremented by 5: 4000, 4005, 4010, etc.