  The fundamental combinatorial structure of a net in CP^2 is its associated
set of mutually orthogonal latin squares. We define equivalence classes of sets
of orthogonal Latin squares by label equivalences of the lines of the
corresponding net in CP^2. Then we count these equivalence classes for small
cases. Finally, we prove that the realization spaces of these classes in CP^2
are empty to show some non-existence results for 4-nets in CP^2.
