How would I assign a variable from another application?

My overall objective is to auto-populate a form with with data already collected in another form.

Normally, I set my variables like this when the form is under the same application:

var = REMOTE_FORM [REMOTE_FIELD == input.LOCAL_FIELD]

LOCAL_1 = var.REMOTE_1

LOCAL_2 = var.REMOTE_2

But, I have an instance where I need to reference a form under another application; HOW?