Codewords for Projective Planes from Sets of Type (s, t)

Let Π* be a projective plane of order n2 having a Baer subplane Π, and let C be the code of Π* over a prime field Fp, where p divides n . If Π contains a set K of type (s, t), then it is shown that the incidence vectors of certain sets of points defined through K are, subject to some congruence relations, in C⊥ , and sometimes in C ∩ C⊥ .