Compromised diagonals and joseki 4

Joseki?  

If Black here comes out with after the unusual pincer , what happens?

Joseki? (Black 11 at a, White 12 at b, Black 13 at c)  

is played too rarely to recognise anything as joseki (except for itself), but the sequence here seems to be one of the candidates, being the only one I saw more or less replicated (although in a game with a black stone at the marked point, so a was not played, while b was not answered).

This (+) is an example of how the staircase sabaki technique is occasionally used to attack.