Chess Board
[ECO code C77]
MORPHY RUY LOPEZ - Anderssen Var.
The Duras Variation
Black, like White, pushed his QP out one square.
White takes an opportunity to advance his QBPawn to QB4(c4) for the Duras line preventing 6..P-QKt4, though 6.P-B3 is a stronger continuation.
    White  Black	White  Black
 1. P-K4   P-K4	     6.	P-B4
 2. Kt-KB3 Kt-QB3
 3. B-Kt5  P-QR3
 4. B-R4   Kt-B3
 5. P-Q3   P-Q3	   Transp.from STDD.
Example ends: Undo or Jump or Clear