This play for White in the 3-4 point low approach two-space high pincer was hardly tried before the 1960s. White looks to settle herself; but there are variations involving a difficult fight.
Black at 1 is now expected - the alternative is Black a.
This is the set continuation, though sometimes Black 4 is played at a instead.
The main ideas now are Black at a, permitting White a slide on the top side, or b denying it. Also played are Black c and d.
If Black 1 here, White in pro games has tried a counter-attack on the left (one of the points a), or at b to take a key point of shape. It seems there is no definitive joseki yet.