I believe papal documents are named simply after their first few words. Do you have the complete latin text, or even the first paragraph? It's a bit hard without any context.
My speculation, for what it's worth, is that the expression might be a future temporal cum clause, where the future perfect indicative is often used, especially when it is followed by a main clause whose action is dependent on completion of the cum clause's action, such as
When x has been given, then y will happen
where x is some suitable ecclesiastical feminine noun agreeing with data
- grace?). But all this is a very long shot when we have only three words!