When partner opens any Preempt from 2 thru 3 (except 3) we play that 4 is Special Keycard
When Partner preempts 3 we play 4 as extending the Preempt and 4 as Special Keycard
Responses to Special Keycard are:
Special Keycard is on over Interference so long as it is a jump. If we cannot jump then 4NT becomes Special Keycard.