# Octonion Grassmanian?

I just learnt that the octonion projective space $$\mathbf{OP}^n$$ exists only for $$n=1,2$$. How about the "octonion Grassmannian", i.e. the space of $$k$$-subspace of $$\mathbf O^n$$? For which values of $$(k,n)$$ does it make sense?