Variables available to the vRO Presentation layer when called from vRA XaaS

Hello,

Are there any default variables available to the vRO Presentation layer while the XaaS form is being filled out?

I am wanting a way to use OGNL to call an action to populate a drop-down filtered by Business Group/subtenant name or user ID so that the returned results are specific to what BG the form was called from.  If there was a built in variable for the Business Group or User ID I could send that to the action as an input to filter the results.

Thanks!