determined by reference to the use of the design is in force under the registered design, then— (a) in relation to any use of the design which, but for this section and section eighteen, would constitute an infringement of the rights of the licensee, subsection (3) of section eighteen shall have effect as if for the reference to the registered proprietor there were substituted a reference to the licensee; and (b) in relation to any use of the design by the licensee by virtue of an authority given under section eighteen, that section shall have effect as if subsection (3) thereof were omitted. (3) Subject to the provisions of subsection (2), where the registered design or the right to apply for or obtain registration of the design has been assigned to the registered proprietor in consideration of royalties or other benefits determined by reference to the use of the design, then— (a) in relation to any use of the design by virtue of section eighteen— (i) subsection (3) of that section shall have effect as if the reference to the registered proprietor included a reference to the assignor; and (ii) any sum payable by virtue of that subsection shall be divided between the registered proprietor and the assignor in such proportions as may be agreed upon between them or as may, in default of agreement, be determined by the Tribunal on a reference under section twenty-one; and (b) in relation to any use of the design made for the service of the State by the registered proprietor to the order of a department of the State, subsection (3) of section eighteen shall have effect as if that use were made by virtue of an authority given under that section. (4) Where, under subsection (3) of section eighteen, payments are required to be made by a department of the State to a registered proprietor in respect of any use of a design, any person being the holder of an exclusive licence under the registered design, not being such a licence as is mentioned in subsection (2) of this section, authorizing him to make that use of the design shall be entitled to recover from the registered proprietor such part, if any, of those payments as may be agreed upon between that person and the registered proprietor or as may, in default of agreement, be determined by the Tribunal on a reference under section twenty-one to be just having regard to any expenditure incurred by that person— (a) in developing the said design; or (b) in making payments to the registered proprietor, other than royalties or other payments determined by reference to the use of the design, in consideration of the licence; and if, at any time before the amount of any such payment has been agreed upon between the department of the State and the registered proprietor, that person gives notice in writing of his interest to the department, any agreement as to the amount of that payment shall be of no effect unless it is made with his consent. 20 Special provisions as to State use during emergency (1) During any period of emergency the powers exercisable in relation to a design by a department of the State or a person authorized by the Minister under section eighteen shall include power to use the design for any purpose which appears to the Minister necessary or expedient— (a) for the efficient prosecution of any war in which Zimbabwe may be engaged; or (b) for the maintenance of supplies and services essential to the life of the community; or (c) for securing a sufficiency of supplies and services essential to the well-being of the community; or (d) for promoting the productivity of industry, commerce or agriculture; or