ASD External Values / Labels

This is a combo vCAC / vRO question. Lets say  I want to have a field on my ASD form, with a type string, and a presentation of Radio Button Group.

I can define manually a list of elements (value AND label):

What i want to do, is create this same behavior but use an external vRO action to define the list of values AND labels. So if i set my action to:

I can get the list to populate correctly, by returning a Array/String from the action:

,

The problem is, it sets the value and the label to the same thing. I want to have a value set to X and a label set to Y. What should my return type be in order to achieve this?

Is there documentation somewhere listing what each ASD form type (checkbox list, date & time, list, dual list, radio button group, search, tree, map) expects for a return type, when set to an external action, in order to properly populate the item on the form?

Thanks as always,

-James