Avoids heavy theory of Ruy Lopez or Italian main lines (like 4.d4). Idea: 0-0, Re1, Nbd2, Nf1–g3, then d4 break.
4.h4!? – provocative but strong, or 4.Nf3 e6 5.Be2 opening repertoire for white
c4 break later, control dark squares.
3...c5 4.exd5 exd5 5.Ngf3 Nf6 6.Bb5+ Bd7 7.Bxd7+ Nbxd7 8.O-O Be7 9.dxc5 Nxc5 10.Nb3 Avoids heavy theory of Ruy Lopez or Italian
5.Nxe5 g6 6.Bc4 Nb6 7.Bb3 Bg7 8.O-O O-O 9.c4 opening repertoire for white
4.Nf3 e6 5.Be2 Nd7 6.O-O Ne7 7.Nbd2