11. (1) Only adult able-bodied males who are of an apparent age of not less than 18 and not more than 45 years may be called upon for forced or compulsory labour. Except in respect of the kinds of labour provided for in Article 10 of this Convention, the following limitations and conditions shall apply: (a) whenever possible prior determination by a medical officer appointed by the administration that the persons concerned are not suffering from any infectious or contagious disease and that they are physically fit for the work required and for the conditions under which it is to be carried out; (b) exemption of school teachers and pupils and officials of the administration in general; (c) the maintenance in each community of the number of adult able-bodied men indispensable for family and social life; (d) respect for conjugal and family ties. 11. (2) For the purposes of subparagraph © of the preceding paragraph, the regulations provided for in Article 23 of this Convention shall fix the proportion of the resident adult able-bodied males who may be taken at any one time for forced or compulsory labour, provided always that this proportion shall in no case exceed 25 per cent. In fixing this proportion the competent authority shall take account of the density of the population, of its social and physical development, of the seasons, and of the work which must be done by the persons concerned on their own behalf in their locality, and, generally, shall have regard to the economic and social necessities of the normal life of the community concerned. Article 12 12. (1) The maximum period for which any person may be taken for forced or compulsory labour of all kinds in any one period of twelve months shall not exceed sixty days, including the time spent in going to and from the place of work. 12. (2) Every person from whom forced or compulsory labour is exacted shall be furnished with a certificate indicating the periods of such labour which he has completed. Article 13 13. (1) The normal working hours of any person from whom forced or compulsory labour is exacted shall be the same as those prevailing in the case of voluntary labour, and the hours worked in excess of the normal working hours shall be remunerated at the rates prevailing in the case of overtime for voluntary labour. 13. (2) A weekly day of rest shall be granted to all persons from whom forced or compulsory labour of any kind is exacted and this day shall coincide as