A positional choice against the Queen's Indian. I played this move several times during the most active years of my career. Nowadays 5.b3 and 5.Qc2 are the most popular.
1. d2d4  1... g8f6  2. c2c4  2... e7e6  3. g1f3  3... b7b6  4. g2g3  4... c8a6 