TINTMLT   Isentropic vertical interpolation flag indicating how a multiple
           occurrence (within a vertical column) of a given potential tempera-
           ture surface is to be handled (one CHARACTER value, default is
           TINTMLT = 'BLOCK').

           'BLOCK' - set all field values to the blocked point value (1.E36)
                     whenever the location of the potential temperature surface
                     is ambiguous. (default)
           'TOP'   - ignore ambiguity and interpolate to the highest (in eleva-
                     tion) potential temperature surface in the column