ages 13 and 15 in paragraph 1 and the age 14 for the age 15 in paragraph 2 of this Article. Article 8 8. (1) After consultation with the organisations of employers and workers concerned, where such exist, the competent authority may, by permits granted in individual cases, allow exceptions to the prohibition of employment or work provided for in Article 2 of this Convention, for such purposes as participation in artistic performances. 8. (2) Permits so granted shall limit the number of hours during which and prescribe the conditions in which employment or work is allowed. Article 9 9. (1) All necessary measures, including the provision of appropriate penalties, shall be taken by the competent authority to ensure the effective enforcement of the provisions of this Convention. 9. (2) National laws or regulations or the competent authority shall define the persons responsible for compliance with the provisions giving effect to the Convention. 9. (3) National laws or regulations or the competent authority shall prescribe the registers or other documents which shall be kept and made available by the employer; such registers or documents shall contain the names and ages or dates of birth, duly certified wherever possible, of persons whom he employs or who work for him and who are less than 18 years of age.