Further split a GAF value within a single field.

def _chk_fld(self, ntd, name, qty_min=0, qty_max=None):
        """Further split a GAF value within a single field."""
        vals = getattr(ntd, name)
        num_vals = len(vals)
        if num_vals < qty_min:
            self.illegal_lines['MIN QTY'].append(
                (-1, "FIELD({F}): MIN QUANTITY({Q}) WASN'T MET: {V}".format(F=name, Q=qty_min, V=vals)))
        if qty_max is not None:
            if num_vals > qty_max:
                self.illegal_lines['MAX QTY'].append(
                    (-1, "FIELD({F}): MAX QUANTITY({Q}) EXCEEDED: {V}\n{NT}".format(
                        F=name, Q=qty_max, V=vals, NT=ntd)))