Select Nested Table Key (Add New Nested Table Wizard)
Applies To: SQL Server 2016
Use the Select Nested Table Key page to select the attribute that will be the key for the nested table.
For More Information: Data Mining Wizard (Analysis Services - Data Mining), Create a Relational Mining Structure
Select the attribute that will be the key column for the nested table. All selected attributes must be in hierarchies or have their attribute hierarchies enabled.