seems to be a very common variation, however, there is no coverage whatsoever on SL. Time to change it. I don't know very much about it, but obviously this is related to the resistance variations of the well-known joseki below
Dieter: it is mentioned at 44PointLowApproachLowExtensionSlidePincer33 that nowadays is often directly at , as in the first diagram above. Perhaps we can work that page for the reason why. If Black plays in this diagram then in the next diagram can lead to complications.