. . . "Permitted employment of children aged 13 5 A child aged 13 may not be employed except in light work in one or more of the following specified categories: (a) agricultural or horticultural work; (b) delivery of newspapers, journals and other printed material, and collecting payment for same, subject to the provisions of byelaw 3(i); (c) shop work including shelf stacking; (d) hairdressing salons; (" .