As is the case with many other items in PeopleSoft, positions are effective dated.  However, unlike other items, the position does not have to have an exact match with corresponding Job Data effective date.  That being the case, it is advisable to allow a "cushion" between the effective date on the position and the Job Data date.  While Job Data allows for multiple rows with the same effective date with the use of the Effective Sequence number, Position Data only allows one row per effective date.  By allowing for that cushion, if subsequent updates need to be made to the position, a later effective-dated row can be added without negatively impacting Job Data.