Hi,
Thanks for the reply. I thought the data field option was supposed to be used as the 3rd unique key value. What is the difference between the managed field option and the data field option under the section for Additional Key Column? If we want to use LabKey, then it seems that we need to modify our original data to make it fit in if we have more than 3 keys. Is there any particular reason why LabKey allows a max of 3 keys? It's common to have more than 3 in clinical study data, especially if following CDISC standards.