Invariant f-structures on the flag manifolds SO(n)/SO(2)xSO(n-3)
  We consider manifolds of oriented flags SO(n)/SO(2)xSO(n-3) (n>=4) as 4- and 6-symmetric spaces and indicate characteristic conditions for invariant Riemannian metrics under which the canonical f-structures on these homogeneous $\Phi$-spaces belong to the classes Kill f, NKf and G_1f of generalized Hermitian geometry. 
Vitaly V. Balashchenko, Anna Sakovich