The @STATUS function returns the status of the solution process using the
following codes:

@StatusCode                        Interpretation
--------------------------------------------------------------------------
     0                             Global Optimum - The optimal
                                   solution has been found.

     1                             Infeasible - No solution exists
                                   that satisfies all constraints.

     2                             Unbounded - The objective can be
                                   improved without bound.

     3                             Undetermined - The solution
                                   process failed.

     4                             Feasible - A feasible solution
                                   was found that may, or may not, be the
                                   optimal solution.

     5                             Infeasible or Unbounded - The
                                   preprocessor determined the model is
                                   either infeasible or unbounded. Turn off
                                   presolving and re-solve to determine
                                   which.

     6                             Local Optimum - Although a
                                   better solution may exist, a locally
                                   optimal  solution has been found.

     7                             Locally Infeasible - Although
                                   feasible solutions may exist, LINGO was
                                   not  able to find one.

     8                             Cutoff - The objective cutoff
                                   level was achieved.

     9                             Numeric Error - The solver
                                   stopped due to an undefined arithmetic
                                   operation in one of the constraints.

Note from LINGO tutorial.

In general, if @STATUS does not return a code of 0, 4 or 7, the solution is
of little use and should not be trusted.
In many cases LINGO will not even  export data to the @POINTER memory
locations if @STATUS does not return one  of these three codes.