Compromised diagonals and joseki 2

Accepted as joseki  

This play has become a standard one in the Chinese opening.

Black does not actually attack the white stone, but tries to avoid helping it make shape in any way. After this, the white stone is light.

making shape  

Because is light, White will often either play tenuki, or jump away lightly; but if White does want to make shape here (immediately or later), this is one standard variation.

The choice between here or at a, as well as the position of , of course depend on the exact position of .