Assessing a rateable value requires a valuation that follows the above process, but the matters to be considered are constrained by legislation. So the physical properties are considered not at the present day, but at the Material Day, and are constrained by the valuation assumptions. The economic conditions are considered at the Antecedent Valuation Date. The valuation is based on a hypothetical lease laid down in the valuation assumptions. The Secretary of State may make regulations for certain classes of property that give a statutory formula for the rateable value, instead of the rental value. These classes include large ports and public utilities.