How about this:
In normal operation (centre picture), the flow in the upper half of the intake was supersonic with a normal shock as required to decelerate to subsonic conditions. In the lower half the flow was decelerated to just sonic by the cowl shock. If the engine demand increased the region of supersonic flow got bigger until it nearly filled the intake (right hand picture).
The small reversed "D" zone just below the bleed slot is the supersonic region. The bleed flow entered the bleed aft of the normal shock.