(b) may at any time formally extend the scope of application by a declaration addressed to the Director-General of the International Labour Office. Article 6 6. This Convention does not apply to work done by children and young persons in schools for general, vocational or technical education or in other training institutions, or to work done by persons at least 14 years of age in undertakings, where such work is carried out in accordance with conditions prescribed by the competent authority, after consultation with the organizations of employers and workers concerned, where such exist, and is an integral part of: (a) a course of education or training for which a school or training institution is primarily responsible; (b) a programme of training mainly or entirely in an undertaking, which programme has been approved by the competent authority; or (c) a programme of guidance or orientation designed to facilitate the choice of an occupation or of a line of training. Article 7 7. (1) National laws or regulations may permit the employment or work of persons 13 to 15 years of age on light work which is: (a) not likely to be harmful to their health or development; and (b) not such as to prejudice their attendance at school, their participation in vocational orientation or training programmes approved by the competent authority or their capacity to benefit from the instruction received. 7. (2) National laws or regulations may also permit the employment or work of persons who are at least 15 years of age but have not yet completed their compulsory schooling on work which meets the requirements set forth in sub-paragraphs (a) and (b) of paragraph 1 of this Article. 7. (3) The competent authority shall determine the activities in which employment or work may be permitted under paragraphs 1 and 2 of this Article and shall prescribe the number of hours during which and the conditions in which such employment or work may be undertaken. 7. (4) Notwithstanding the provisions of paragraphs 1 and 2 of this Article, a Member which has availed itself of the provisions of paragraph 4 of Article 2 may, for as long as it continues to do so, substitute the ages 12 and 14 for the