Yes, did you watch the entire video? The entire reason for adding that letter to the ID is because you need a unique value for each row, for each record in that combo box. Just having another data type won't do it. I suppose you could combine that ID with another value like that into another calculated field, but why bother? Just making a unique ID that's a combination of the existing ID plus a letter works perfectly fine.

Oh, yes, the video and the method made sense. I've been in a habit of using a field in union queries to track data types, so this was new to me, I was intrigued, and I was trying to think more broadly what the pros/cons of the two approaches would be.

Michael it's basically so that you have a unique field for each record. So you can select it with a combo box. Other than that, it's not really necessary.