Article 290. Coverage and employees' right to self-organization. — All persons employed in commercial, industrial and agricultural enterprises and in religious, charitable, medical or educational institutions whether operating for profit or not, shall have the right to self-organization and to form, join or assist labor organizations of their own choosing for purposes of collective bargaining. Ambulant, intermittent and itinerant workers, self-employed people, rural workers and those without any definite employers may form labor organizations for the purpose of enhancing and defending their interests and for their mutual aid and protection.