In this paper we study special mappings between n-dimensional (pseudo-)
Riemannian manifolds. In 2003 Topalov introduced PQ?-projectivity of
Riemannian metrics, with constant ? ? 0,1 + n. These mappings were studied
later by Matveev and Rosemann and they found that for ? = 0 they are
projective. These mappings could be generalized for case, when ? will be a
function on manifold. We show that PQ?- projective equivalence with ? is a
function corresponds to a special case of F-planar mapping, studied by Mikes
and Sinyukov (1983) with F = Q. Moreover, the tensor P is derived from the
tensor Q and non-zero function ?. We assume that studied mappings will be
also F2-planar (Mikes 1994). This is the reason, why we suggest to rename
PQ? mapping as F?2. For these mappings we find the fundamental partial
differential equations in closed linear Cauchy type form and we obtain new
results for initial conditions.