It doesn't mather if you already have a primary key or not. You can have any number of candidate key as you wish. The advantage of using a candidate key is that you let VFP resolve conflict and you will be sure that the value will be unique even in a multi-user scenario.

>I don't think the field needs to be a candidate, I have a primary key in the table already. I would like to let the user know that there is a conflict with the ID number though. There are approx 800 drawings that need to be entered into the table and all have their own ID already. There may be problems that surface when inputting that need to addressed. The problem is that when the valid returns .t. it doesn't tab off the field.