[ECO code E24]
(The) Side Variation
Black's Kt5(b4) Bishop retreats to QR4(a5) to maintain the pin on White's QKt - a disastrous move losing him the bishop, as White will invariably trap it by 5.P-QKt4 (and if then 5..B-Kt3..P-B5). B-Alt.
White Black 1. P-Q4 Kt-KB3 2. P-QB4 P-K3 3. Kt-QB3 B-Kt5 4. P-QR3 B-R4?? ??=bad move
Example ends: Undo or Jump or Clear