59 to 63; (3) that the bill served on the Mills was not in accordance with the Rules; (a) to the extent that the said bill sought to assess open lands , (b) that the flat rate method on carpet area was not permissible as it was not a recognised method of determining the annual letting value and (c) that the assessing officer had arrived at the annual letting value on the basis of construction cost without giving an opportunity, to the Company to be heard on such cost; (4) that as the authentication was made to the assessment list on March 6, 1964 it could not operate under the said Rules for assessment for the period prior thereto, viz., April 1, 1963 to 'March 31, 1964 and lastly; (5) that the assessment suffered from discrimination inasmuch as the assessing officer assessed the Century Mills on the basis of construction cost while he did so in the case of the other companies at a flat rate on the carpet area occupied by them.