What is Data Date in Primavera? Well, it is very easy to learn about Data Date is in Primavera P6.
Data Date is the date until which the activities have progressed. Let's say you have an activity to build a wall in 1 month and someone asks you that how much wall you have built? If you answer 50%. He will not understand whether you are on schedule or not. So the questioner again asks, 50% in how much time, and you answer that you built 50% in 1st week (say, day 7th) of the month, the questioner then will understand that you are ahead of schedule. 50% was actually expected to be completed by 15th of the month.
Lets look at a different scenario. There is another wall, to be built in 1 month. Someone asks you how much you have built it so far and you answer 50%. He further asks that you have built 50% of it in how much time and you answer that 50% is built in 3rd week of the month (say, day 21st). The questioner now understands that you are going slow because 50% had to be completed by 15th of the month.
So, the day until you have done the work is Data Date. In the above example, day 7 and day 21 were Data Dates for the activities.
Hence, after you enter progress for your activities, you must enter Data Date to specify that the progress you have entered is accomplished until what date. By entering Data Data, Primavera determines whether you are ahead or behind schedule, and reschedules the activities, to either finish on date as planned, finish earlier or later than the baseline date, depending on how much your activity has progressed until the Data Date, while comparing also the baseline.