Alternate Structures - Issues creating alternate structure.

Summary

Need to explore use of alternate structures until full ECO is ready

Content

Hello, 

I need to create an alternate item structure. When I navigate to PIM--> Structure --> Create New Item Structure, I am not able to select a new 'name' for the structure. See attached image. 

Where would I manage the list of values for this drop down so I am able to create an alternate structure? I was not able to find a step-by-step on Oracle documentation to create alternate structures. 

Business use case is:

ECO without revision change does not allow BOM QTY change. I need to create an alternate structure that will swap out component A for component B. The change is only for a small packaging assembly component, and does not change the form or function of the item itself.