What is the function of activating an individual elevator on the B-1B Lancer? This B-1B Lancer's picture I captured from this Youtube video. The control axes is from Wikipedia.

As we know, the three "conventional" axes are as follows:


Roll axis controlled by aileron,
Pitch axis controlled by elevators (both at the same time),
Yaw axis controlled by rudder.


Then my questions are:


What is exactly that purpose (the single elevator activation), and
How it work? Is there new axis of it?
That would be the correct control response for a combined roll to the right and nose up pitch command from the pilot. It looks like that photograph was taken while the pilot was in the middle of doing a check of their control services prior to taxi.

You can see similar results in the tower buzz sequence out of Top Gun. The final bit shows an F-14 from the tail which rolls to the right and pitches nose up with a similar control response from a combination of the tailplane and starboard wing spoilers.