Orthodox Defense, Swiss, Carlsbad Variation

The Carlsbad Variation arises when White answers 7...a6 in the Orthodox Defense with an immediate 8. cxd5. The exchange releases the central tension before Black can use the prepared ...dxc4 and queenside expansion. The usual 8...exd5 gives the Carlsbad pawn structure known from the Exchange Variation, with White holding the half-open c-file. The less common 8...Nxd5 aims to simplify. The line is rarely played, and the engine rates it as roughly balanced.