I. Right to strike
If an employee is a member or an officer of a trade union, he or she will have the right to take part in the activities of the trade union at any appropriate time. Appropriate time means either (a) outside working hours, or (b) during working hours by arrangement and with the consent of the employer.
However, "the activities of the trade union" does not necessarily mean "strike". For example, an internal meeting of the trade union for discussion about a possible strike is not a "strike". For the meaning of "strike", see the answer to the question below.