  B0943+10 is known to switch between two distinct, hours-long modes of radio
emission, Bright (B) and Quiet (Q). Up to now the switches in both directions
were believed to occur instantly (on the scale of a spin period). We have found
a transitive process around the Q-to-B-mode switch, which consists of two
additional short-lived modes, each with distinct average profiles and subpulse
drift rates. Based on observations at low radio frequencies, we examine the
properties of these transitive modes and discuss their implications in the
framework of the traditional carousel model of drifting subpulses.
