  The stagnation point flow toward a rotating disk of finite radius is known to
develop -- near the edge of the disk -- into a triple deck structure when the
flow is strictly a stagnation point flow, and into a double deck structure when
the flow is strictly a rotating disk flow. It is shown here that the transfer
from one structure to another is singular; requiring matching of two main
decks. The double deck structure is, in essence, a triple deck structure with
collapsing upper deck.
