3-4 point high approach low extension, trick play
The inside hane of is supposed to be a trick play: see
3-4 point high approach low extension for the refutation, however see also 3-4 point high approach low extension, whole board for more discussion.
Now why exactly is White tricked ? Because she has to mind her cutting stones while her corner is not alive. Indeed, if Black has got enough outside liberties (due to White's fleeing for safety) ...
Black descends with , then hanes at
. White can't reply at a due to shortage of liberties.
Maybe this trick play has already been described here. -- Dieter