Charles Matthews You could characterise here as a probe, perhaps. Black is very strong, locally, though. The intention might be to play some forcing moves, if Black reacts in a submissive fashion.
Black's first reaction ought to be here. After
Black has to decide whether to carry on at a or play solidly at b. Allowing White to play at a works so well with
that Black really must play at a himself.
Considering how that variation went, here is attractive. It is not now obvious that White can live in the corner, since Black is strong immediately above.