A table can optionally have Field Groups. In NAV 2016 you have two types of Field Groups:
– Dropdown: determines which fields will be displayed when a table lookup will occur in the Windows Client
– Brick: the layout will change dynamically based on the type of device you are using (tablet client, phone client, web client). Want to know more? Please check the MSDN at https://msdn.microsoft.com/en-us/library/mt299400(v=nav.90).aspx
When there are no Field Groups defined, the first two fields of the primary key will be displayed and the first text field when the table will be ‘looked up’ in a DropDown.