Where the laws of a Member State permit a company to acquire its own shares, either itself or through a person acting in his own name but on the company's behalf, they shall make such acquisitions subject to at least the following conditions: (a) authorization shall be given by the general meeting, which shall determine the terms and conditions of such acquisitions, and in particular the maximum number of shares to be acquired, the duration of the period for which the authorization is given and which may not exceed 18 months, and, in the case of acquisition for value, the maximum and minimum consideration.