This section has aerofoils suitable for the fuselage fairing or streamlining tubes.
These sections will normally be operating at or close to zero degrees.
The selection criteria is rather different to the wings in that it has to accommodate the pilot and structure and the forces on it are low but it streamlines the pilot, also the pilot has to be able to see out.
The drag is not as important as with the wings as the streamlined fuselage only adds about a 1/5th or less of the total drag..
A value of 21% thickness has been chosen as typical.