[ECO code D15]
(The) Side Variation
Black is unwise to develop his Queen's Bishop to KKt5(g4) half-pinning White's KKt, as 5.Kt-K5..B-B4, 6.PxP..PxP, 7.P-K4! (planning Q-Kt3) refutes it outright (e.g. Black is soon forced to forego castling). B-Alt.
White Black 1. P-Q4 P-Q4 2. P-QB4 P-QB3 3. Kt-KB3 Kt-B3 4. Kt-B3 B-Kt5?
Example ends: Undo or Jump or Clear