Patents [CAP.400 41 (9) The terms of any exclusive licence ordered to be granted under subsection (8) shall, with due regard to the risks to be under­ taken by the licer.see in providing the capital and working the inven­ tion. be so framed as­ (1I) to secure to the patentee the maximum royalty compatible with the successful working of the invention within Zambia on a commercial scale and at a reasonable profit; (b) to guarantee to the patentee a minimum yearly sum by way of royalty, if and so far as it is reasonable to do so; and in addition to any other terms of the licence or order, the licence and the order shall be made revocable at the discretion of the High Court if the licensee fails to­ (i) work the invention within the time specified in the order; (ii) expend the amount specified in the licence as being the amount which he is able and willing to provide for the purpose of working the invention on a com­ mercial scale within Zambia; or (iii) pay to the patentee the royalties payable in terms of the licence. (10) In deciding to whom an exclusive licence is to be granted, the High Court shall. unless good reason is shown to the contrary, prefer an existing licensee to a person who, according to the register, has no interest in the patent. (II) The order directing the grant of an exclusive licence under this section shaIl operate to divest the patentee of any right which he may have as patentee to work or use the invention, and to revoke all existing licences, unless otherwise provided in the order, and may, if considered fair and equitable by the High Court, be made subject to the condition that the licensee shall give proper compensation to be fixed by-the High Court for any money or labour expended by the patentee or any existing licensee in developing or working the invention. (12) A licensee under this section shall be entitled to call upon the patentee concerned to institute any proceedings which may be nec­ essary to prevent infringement of the patent in question and shall in all other respects have the same rights as any other licensee, and if the patentee fails within two months after being called upon by the licensee. or within such further period as the High Court may allow, to institute any such proceedings, the licensee may himself institute such proceedings as if he were the patentee, making the patentee a defendant. but the patentee shall not be liable for any costs in con­ nection with such proceedings unless he enters an appearance and takes part in those proceedings.