Fokker M.19, M.21, M.22, D.III, D.IV and D.V

The Fokker M.19 was a reasonably successful Fokker biplane that entered German service as the Fokker D.III, but was mainly used as a training aircraft.
The Fokker M.21 was a biplane fighter aircraft based on the earlier Fokker D.I but powered by the 160hp Mercedes D.III engine.
The Fokker M.22 was a Fokker biplane developed in the autumn of 1916 and accepted by the German army as a training aircraft with the designation Fokker D.V.
The Fokker D.III was the German army designation for the Fokker M.19 biplane, initially ordered in 1916 as a fighter, but soon relegated to training duties.
The Fokker D.IV was the German army designation for the M.21 biplane, a fighter aircraft that appeared at almost the exact moment that the long-running quality control problems with Fokker aircraft resulting in them being withdrawn from front line service.
The Fokker D.V was the German army designation for the Fokker M.22 biplane, ordered as a training aircraft in October 1916.