2 NT Opening and its anwers

The auction so far

2 nt	20-21 nt	3	Transfer relay to 3NT
3 nt	Relay	4	SI
???

2 nt Printversion

No answers are found / defined. If the basic distribution is known you can ask for exact distribution with Symmetric relay principles. After that the next relay asks for Keycards and the relay after that for the exact controls in specific suit