Chess Board
[ECO code C24]
TRANSPOSITION
BISHOP'S OPG. (Berlin D.) to VIENNA OPG. (Stanley)
Black developed his KKt to attack White's KP (a hallmark of any Berlin), contest for Q4(d5) and prevent a "Scholar's" 3.Q-KR5(h5).
White transposes into the Stanley Variation of a Vienna Game by deploying his Queen's Knight to defend his endangered KP and deter 3..P-Q4. W-Alt. 
    White  Black    Transp.White Black
 1. P-K4   P-K4     (1.	P-K4   P-K4  )
 2. B-B4   Kt-KB3   (2.	Kt-QB3 Kt-KB3)
 3. Kt-QB3	    (3.	B-B4	     )
Continue: Transpose or Undo or Jump or Clear